Image capturing apparatus and accessories

ABSTRACT

An image capturing apparatus on which, and from which, an accessory is mountable and dismountable includes a plurality of terminals disposed in a circumferential direction of a mount, and a terminal holder. The terminal holder has a height level difference for holding the terminals at different positions in a center-axis direction of the mount. The terminals include a first terminal configured to be used to supply power for driving an internal component of the accessory, and a second terminal configured to indicate a ground level corresponding to the first terminal. The second terminal is disposed nearer in a mount direction of the accessory than the other terminals on a predetermined stage of the terminal holder, and is connected to a corresponding one of a plurality of terminals of the accessory first among the terminals when the accessory is mounted on the image capturing apparatus.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an image capturing apparatus andaccessories each including a mount provided with terminals that enableelectrical connection to another device.

Description of the Related Art

It is commonly known that an accessory (camera accessory) that can bemounted on and dismounted from an image capturing apparatus is suppliedwith power from the image capturing apparatus or performs communicationto exchange, for example, various commands and data with the imagecapturing apparatus in a state where the accessory is mounted on theimage capturing apparatus. In general, for power supply andcommunication as described above, a mount portion called a mount of theimage capturing apparatus and that of the accessory are each providedwith a plurality of terminals, the plurality of terminals of one of themounts being electrically connected to those of the other mount whencoming into contact with those of the other mount. The plurality ofterminals may perform communication independently of one another usingdifferent communication systems respectively.

For example, Japanese Patent Laid-Open No. 2014-038300 discloses atechnique for a terminal arrangement in which, in a case of mounting ordismounting an accessory on or from an image capturing apparatus with abayonet coupling mechanism, a terminal provided in the image capturingapparatus for detecting mounting of the accessory does not slide on apower-supply-system terminal provided in the accessory.

SUMMARY OF THE INVENTION

An image capturing apparatus according to an aspect of the presentinvention is an image capturing apparatus including a second mountconfigured to allow coupling to a first mount included in an accessory,the accessory being mountable on and dismountable from the imagecapturing apparatus by rotating the first mount relative to the secondmount in a circumferential direction. The second mount includes aplurality of terminals disposed in a circumferential direction of thesecond mount and configured to be used in electrical connection, and aterminal holder configured to hold the plurality of terminals. Theterminal holder has a height level difference for holding the pluralityof terminals at different positions in a center-axis direction of thesecond mount. The plurality of terminals include a first terminalconfigured to be used to supply power for driving an internal componentof the accessory, and a second terminal configured to indicate a groundlevel corresponding to the first terminal. The second terminal isdisposed nearer in a mount direction of the accessory than the otherterminals of the plurality of terminals on a predetermined stage of theterminal holder, and is connected to a corresponding one of a pluralityof terminals of the accessory first among the plurality of terminalswhen the accessory is mounted on the image capturing apparatus.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram illustrating types of camera accessories thatcan be mounted on a camera body.

FIG. 2 is a block diagram illustrating a camera system that includes afirst interchangeable lens and the camera body to which the firstinterchangeable lens can be directly coupled.

FIG. 3 is a block diagram illustrating the internal configuration of thefirst interchangeable lens and that of the camera body in a state wherethe first interchangeable lens is connected to the camera body.

FIGS. 4A and 4B are diagrams illustrating the structure of a cameramount and that of a lens mount.

FIGS. 5A to 5C are diagrams each illustrating the state of connectionbetween terminals in a case of rotating a camera mount and a lens mountrelative to each other.

FIG. 6 is a block diagram illustrating a state where a secondinterchangeable lens is mounted on the camera body with an adaptortherebetween.

FIGS. 7A and 7B are diagrams illustrating a camera mount and a lensmount.

FIGS. 8A and 8B are diagrams illustrating the state of connectionbetween mounts in a case of mounting the second interchangeable lens onthe camera body with the adaptor therebetween.

FIG. 9 is a block diagram illustrating a state where the firstinterchangeable lens is mounted on the camera body with an intermediateaccessory therebetween.

FIGS. 10A and 10B are diagrams illustrating the state of connectionbetween mounts in a case of mounting the first interchangeable lens onthe camera body with the intermediate accessory therebetween.

FIGS. 11A to 11E are diagrams each illustrating the state of connectionbetween a TYPE_IN terminal of the camera body and a camera accessory.

FIG. 12 is a flowchart illustrating an operation up to the start offirst communication when a camera accessory is mounted on the camerabody.

FIG. 13 is a flowchart illustrating operations relating to secondcommunication.

FIG. 14 is a timing chart illustrating broadcast communication in thirdcommunication.

FIG. 15 is a timing chart illustrating P2P (peer-to-peer) communicationin third communication.

FIGS. 16A and 16B are diagrams illustrating the internal configurationof a CS terminal, a DCA terminal, and a DGND terminal in a camera mountand in a lens mount.

FIGS. 17A to 17D are diagrams each illustrating an effect, produced inan electric circuit, that differs depending on a terminal that isdisposed adjacent to an LCLK terminal.

FIG. 18 is a diagram illustrating the internal structure of a cameramount of the camera body.

FIGS. 19A and 19B are perspective views and illustrate the externalappearance of a camera body and a first interchangeable lens.

FIG. 20 is a disassembled perspective view of a mount mechanismaccording to a modification of the present invention.

FIGS. 21A through 21C are diagrams for exemplarily describing anon-coupled state of the mount mechanism according to the modificationof the present invention.

FIGS. 22A through 22C are diagrams for exemplarily describing a coupledstate of the mount mechanism according to the modification of thepresent invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings. Each of the embodiments of the presentinvention described below can be implemented solely or as a combinationof a plurality of the embodiments or features thereof where necessary orwhere the combination of elements or features from individualembodiments in a single embodiment is beneficial.

Connection System of Image Capturing Apparatus and Camera Accessories

An embodiment of the present invention is described below with referenceto FIG. 1 through FIG. 22C.

First, example connections between an image capturing apparatus andcamera accessories employing a lens interchange method are describedwith reference to FIG. 1. FIG. 1 is a system diagram illustrating typesof camera accessories that can be mounted on a camera body 100. Examplesof camera accessories include an interchangeable lens, an adaptor, andan intermediate accessory each including an accessory mount that can becoupled to a camera mount provided in the image capturing apparatus.Specifically, the accessory mount described above has a plurality ofaccessory tabs and a plurality of accessory recesses that can engagewith a plurality of camera tabs and a plurality of camera recessessequentially disposed in the camera mount in a circumferential directionsubstantially orthogonal to the optical axis. The accessory mount in afitting state where the tabs and recesses of the accessory mount fitinto the recesses and tabs of the camera mount can enter an engagingstate where the tabs of the accessory mount engage with the tabs of thecamera mount in the optical-axis direction. The fitting state is acamera accessory mounting start state described below and the engagingstate is a camera accessory mounting (attaching) completion statedescribed below.

Camera accessories that can be connected to the camera body 100 aredescribed with reference to FIG. 1. A first interchangeable lens 200 isone of the camera accessories that can be mounted directly on the camerabody 100 and includes a lens mount B, which is an accessory mount thatcan be directly coupled to a camera mount of the camera body 100described below. An intermediate accessory 500 is one of the cameraaccessories that can be mounted directly on the camera body 100 andincludes the lens mount B, which is an accessory mount that can bedirectly coupled to the camera body 100, and a camera mount A, which canbe coupled directly to the first interchangeable lens 200. That is, thefirst interchangeable lens 200 can also be connected to the camera body100 with the intermediate accessory 500 therebetween.

Further, a second interchangeable lens 300 can be mounted indirectly onthe camera body 100 with an adaptor 400 therebetween, which can bemounted directly on the camera body 100. That is, a lens mount D, whichis an accessory mount provided in the second interchangeable lens 300,is not capable of being coupled directly to the camera mount A providedin the camera body 100. A camera mount C provided in the adaptor 400 canbe coupled directly to (mounted directly on) the lens mount D of thesecond interchangeable lens 300.

As described above, on the camera body 100, the first interchangeablelens 200, the first interchangeable lens 200 with the intermediateaccessory 500 therebetween, and the second interchangeable lens 300 withthe adaptor 400 therebetween, can be mounted. Hereinafter, in adescription common to the first interchangeable lens 200 and the secondinterchangeable lens 300, the first interchangeable lens 200 and thesecond interchangeable lens 300 are each simply referred to as aninterchangeable lens. Similarly, the adaptor 400 and the intermediateaccessory 500 are each simply referred to as an adapter.

Basic Configuration of Camera Body 100 and First Interchangeable Lens200

Next, the basic configuration of the camera body 100 and the firstinterchangeable lens 200 is described with reference to FIG. 2. FIG. 2is a block diagram illustrating a camera system that includes the firstinterchangeable lens 200 and the camera body 100 to (on) which the firstinterchangeable lens 200 can be directly coupled (mounted). Although, itshould be understood that in this embodiment, the image capturingapparatus (for example the camera body 100) and the camera accessory(for example the first interchangeable lens 200) are attachable anddetachable from each other. In FIG. 2, a mount provided in the firstinterchangeable lens 200 and a mount provided in the camera body 100 arecollectively referred to as a mount portion 1. The mount provided in thefirst interchangeable lens 200 and the mount provided in the camera body100 will be described in detail below.

The camera body 100 is an image capturing apparatus, typically, adigital camera. As illustrated in FIG. 2, the camera body 100 includes acharge-storage-type solid-state image sensor (hereinafter simplyreferred to as an image sensor) 12, which photoelectrically converts anoptical image of an object formed by a lens 10 provided within the firstinterchangeable lens 200 to output an electrical signal. The camera body100 further includes an A/D converter 13, which converts an analogelectrical signal output from the image sensor 12 to a digital signal,and an image processor 14, which performs various types of imageprocessing on the digital signal to generate an image signal. The imagesignal (still image or moving image) generated by the image processor 14can be displayed on a display 15 and recorded to a recording medium 16.

The camera body 100 further includes a memory 17, which functions as abuffer used when an image signal is processed and which stores anoperation program used by a camera controller 101 described below.

The camera body 100 further includes a camera operation input unit 18,which includes a power switch for turning on and off the power, an imagecapture switch (release switch) for starting recording of an imagesignal, and a selection/setting switch for setting in various menus. Thecamera body 100 further includes the camera controller 101, whichincludes a microprocessor (CPU) that centrally controls operations ofthe camera body 100 and camera accessories that can be mounted on thecamera body 100. For example, the camera controller 101 performs varioustypes of setting on the basis of signals input from the camera operationinput unit 18 or controls communication with a first lens controller 201included in the first interchangeable lens 200 via the mount portion 1.

The first interchangeable lens 200 includes the lens 10, which isconstituted by optical members including a group of a plurality oflenses, such as a zoom lens, a shift lens, and a focus lens, and a lightamount adjusting member, such as a diaphragm. The first interchangeablelens 200 further includes a lens drive unit 11. The lens drive unit 11includes an actuator that moves the optical members, namely, the groupof a plurality of lenses and the diaphragm, or makes the optical membersoperate, and drives the actuator. The first interchangeable lens 200further includes the first lens controller 201, which includes a lensmicroprocessor (LCPU) that centrally controls operations of the firstinterchangeable lens 200. For example, the first lens controller 201controls communication with the camera controller 101 via the mountportion 1 or controls the lens drive unit 11.

Basic Configuration of Electrical Terminals

Now, the internal configuration of the camera in a state where thecamera body 100 and the first interchangeable lens 200 are connected toeach other is described with reference to FIG. 3. FIG. 3 is a blockdiagram illustrating the internal configuration of the firstinterchangeable lens 200 and that of the camera body 100 in a statewhere the first interchangeable lens 200 is connected to the camera body100. The camera mount and the lens mount each include a lock mechanism,a mount holding mechanism, and a plurality of electrical terminals. Thedetails of these mounts will be described below.

As illustrated in FIG. 3, the mount portion 1 includes a plurality ofterminals that enable electrical connection between the camera body 100and the first interchangeable lens 200. The plurality of terminals inthe camera body 100 (camera-side terminals) are exposed outside thecamera body 100 as a plurality of electrical contact pins provided on acontact holding member 105, which corresponds to a terminal holder ofthe camera mount A having a ring shape, as illustrated in FIG. 4A. Theplurality of terminals in the first interchangeable lens 200(accessory-side terminals) are exposed outside the first interchangeablelens 200 as a plurality of electrical contact faces provided on acontact face holding member 205, which corresponds to a terminal holderof the lens mount B having a ring shape, as illustrated in FIG. 4B. In astate where the first interchangeable lens 200 is mounted on the camerabody 100, each contact among the electrical contact pins of the camerabody 100 is electrically connected to a corresponding contact among theelectrical contact faces of the first interchangeable lens 200.

The mounts each have a height level difference in the optical-axis (thecenter axis of the mount) direction so that the position at whichcorresponding terminals, among the plurality of terminals formed on eachmount, come into contact with each other differs in the optical-axisdirection of the mounts as described below. The plurality of terminalsare formed into a unit as a single component, and the terminals in eachmount is connected to a flexible printed board as a single wiring unit.

FIG. 18 is a diagram illustrating the internal structure of the cameramount A of the camera body 100. For example, the terminals areelectrically connected to one another via a single flexible printedboard 106, as illustrated in FIG. 18, and are connected to an internalboard (not illustrated) provided within the camera body 100. Atpositions, in the contact holding member 105, where the terminals areheld, a plurality of holes through which the terminals can be insertedare provided, and terminals 1001 to 1012, which are the camera-sideterminals, are inserted into the plurality of holes respectively. Inthis state, a retaining plate 107 retains the terminals on an objectside in the optical-axis direction (on a mount contact surface side),and screws 108 a, 108 b, and 108 c, which pass through the through holesof the retaining plate 107, are tightened into the contact holdingmember 105.

In this embodiment, the single-unit structure of the camera mount A inthe camera body 100 has been described. In the other mounts describedbelow, at least the same structure in which a plurality of terminals areelectrically connected to a single flexible printed board (wiring) isemployed.

In this structure, the terminals can be collectively disposed atpositions away from an aperture provided in front of the image sensor 12unlike a case where a group of terminals of each mount is divided into aplurality of units and interspersed in the circumferential direction ofthe mount. Therefore, for example, in a case where unwanted light isincident on the camera mount in a state where a camera accessory ismounted on the camera body 100, an effect of the unwanted lightreflected by the terminals formed of a metallic material on imagecapturing of an object can be reduced. Further, the terminals are formedinto a single unit, and therefore, wiring within the image capturingapparatus and the camera accessories becomes less complicated, and themounts can be easily assembled.

Now, the functions of terminals common to the camera mount A and thelens mount B are described. VDD terminals 1001 and 2001 are power supplyterminals for supplying communication control power (VDD), which iscommunication power used mainly in communication control, from thecamera body 100 to a camera accessory (for example, the firstinterchangeable lens 200). The voltage of the power to be supplied tothe first interchangeable lens 200 is set to 5.0 V.

VBAT terminals 1002 and 2002 are power supply terminals for supplyingdriving power (VBAT), which is driving power used in operations of amechanical drive unit of the actuator used to drive the diaphragm andthe focus lens, from the camera to the camera accessory. In other words,the VBAT terminals 1002 and 2002 are terminals used to supply powerother than the communication power. The voltage of the power to besupplied to the first interchangeable lens 200 is set to 4.5 V. The VDDterminals and the VBAT terminals described above are power-supply-systemterminals for supplying power from the camera body 100 to a cameraaccessory. The voltage to be applied to the VBAT terminals may bechangeable depending on the type of accessory mounted on the camera body100, by changing the output setting of a power supply circuit.

DGND terminals 1012 and 2012 are ground terminals corresponding to thecommunication control power VDD. That is, the DGND terminals 1012 and2012 are terminals that indicate (the voltage) of a ground levelcorresponding to the predetermined terminals. In this embodiment,grounding means to set the voltage level of a ground terminal to a level(ground level) substantially equal to the level of the negative pole ofa power supply, such as a battery.

PGND terminals 1004 and 2004 are terminals that indicate a ground levelcorresponding to a terminal of the camera body 100 and that of amechanical drive system including a motor (actuator) provided in acamera accessory (for example, the first interchangeable lens 200). Thatis, the PGND terminals are ground terminals corresponding to the drivingpower VBAT. The DGND terminals and the PGND terminals described aboveare ground terminals for grounding the power supply system of the camerabody 100 and that of a camera accessory to the ground levels.

MIF terminals 1005 and 2005 are terminals for detecting mounting of acamera accessory (for example, the first interchangeable lens 200) onthe camera body 100. The camera controller 101 detects a voltage levelindicated by the MIF terminals to detect mounting or removal of a cameraaccessory on or from the camera body 100. After the camera controller101 has detected, for example, mounting of a camera accessory as aresult of the detection, the camera controller 101 performs control tostart supplying power to the power-supply-system terminals and to startcommunication between the camera body 100 and the camera accessory.

TYPE terminals 1003 and 2003 are terminals for determining the type ofcamera accessory (for example, the first interchangeable lens 200)mounted on the camera body 100. The camera controller 101 detects thevoltage value of a signal indicated by the TYPE terminals and determinesthe type of camera accessory mounted on the camera body 100 on the basisof the value. In the first interchangeable lens 200, the TYPE terminalis pull-down connected to the DGND terminal with a predeterminedresistance described below. The resistance differs depending on the typeof camera accessory.

Now, terminals for various types of communication between the camerabody 100 and a camera accessory are described. A plurality ofcommunication terminals provided in the mount portion 1 are divided intoa plurality of communication systems (groups), and the communicationsystems can perform communication independently of each other. In thisembodiment, LCLK terminals 1008 and 2008, DCL terminals 1006 and 2006,and DLC terminals 1007 and 2007 constitute a first communication unitperforming first communication. DLC2 terminals 1009 and 2009 constitutea second communication unit performing second communication independentof the first communication unit. CS terminals 1011 and 2011 and DCAterminals 1010 and 2010 constitute a third communication unit performingthird communication independent of the first and second communicationunits. In this embodiment, the camera controller 101 and the first lenscontroller 201 can perform the independent first to third communicationvia the plurality of communication terminals described above.

The LCLK terminals 1008 and 2008 are terminals of the firstcommunication unit. The LCLK terminals 1008 and 2008 are terminals for acommunication clock signal output from the camera body 100 to the cameraaccessory and are terminals for the camera body 100 to monitor the busystate of the accessory.

The DCL terminals 1006 and 2006 are terminals of the first communicationunit and are communication data terminals for two-way communicationbetween the camera body 100 and the camera accessory.

The DLC terminals 1007 and 2007 are terminals of the first communicationunit and are terminals for communication data output from the cameraaccessory (for example, the first interchangeable lens 200) to thecamera body 100.

The signal output system of the above-described LCLK terminals, DCLterminals, and DLC terminals corresponding to the first communicationunit can be switched between a complementary metal oxide semiconductor(CMOS) output type and an open type. The CMOS output type in thisembodiment is a type in which switch output is present for both H (High)and L (Low) indicated by a voltage. The open type is a type in whichswitch output is present on only the L side. The open type in thisembodiment is an open drain type but may be an open collector type.

The DLC2 terminals 1009 and 2009 are terminals of the secondcommunication unit and are terminals for communication data output fromthe camera accessory (for example, the first interchangeable lens 200)to the camera body 100.

The DCA terminals 1010 and 2010 are terminals of the third communicationunit and are communication data terminals for two-way communicationbetween the camera body 100 and the camera accessory (for example, thefirst interchangeable lens 200).

The CS terminals 1011 and 2011 are terminals of the third communicationunit and are signal terminals for requesting communication between thecamera body 100 and the camera accessory (for example, the firstinterchangeable lens 200). In this embodiment, in a case where the firstinterchangeable lens 200 is mounted on the camera body 100, thecommunication voltage at the terminals corresponding to the first tothird communication units is set to 3.0 V.

Structure of Mount Portion 1

Now, the structure of the mount portion 1 including the camera mount Aand the lens mount B is described with reference to FIGS. 4A and 4B andFIGS. 5A to 5C. FIGS. 4A and 4B are diagrams illustrating the structureof the camera mount A and that of the lens mount B. FIG. 4A is a frontview of the camera mount A provided on the camera body 100, and FIG. 4Bis a front view of the lens mount B provided on the firstinterchangeable lens 200. FIGS. 5A to 5C are diagrams each illustratingthe state of connection between terminals in a case of rotating thecamera mount A and the lens mount B relative to each other. FIG. 5Aillustrates a mounting-start state of the camera mount A and the lensmount B, FIG. 5B illustrates a mounting-intermediate state of the cameramount A and the lens mount B, and FIG. 5C illustrates amounting-completion state of the camera mount A and the lens mount B.FIGS. 5A to 5C illustrate states where the terminals provided on themounts are viewed in a direction orthogonal to the optical axis of thecamera mount A and the lens mount B. The optical axis described above isparallel to a center axis that passes through the center of the openingof the camera mount A and that of the lens mount B.

The state illustrated in FIG. 5A is a state where a plurality of tabsprovided in the camera mount A are inserted into a plurality of recessesprovided in the lens mount B, and a plurality of tabs provided in thelens mount B are inserted into a plurality of recesses provided in thecamera mount A. In this state, the camera mount A and the lens mount Bare rotated relative to each other in a lens mount direction (attachabledirection). Note that the lens mount direction (mount direction) isorthogonal to the center axis of the camera mount A (or the lens mountB). Then, a transition to a state where the terminals provided on one ofthe mounts are respectively connected to the corresponding terminalsprovided on the other mount, as illustrated in FIG. 5C, occurs. In thestate illustrated in FIG. 5C, relative rotation of the camera mount Aand the lens mount B is stopped by a lock mechanism (not illustrated)that is a rotation stopping member provided in each mount.

FIGS. 19A and 19B are perspective views and illustrate the externalappearance of the camera body 100 and the first interchangeable lens200. FIG. 19A illustrates a state where the first interchangeable lens200 is mounted on the camera body 100, and FIG. 19B illustrates a statewhere the first interchangeable lens 200 is detached from the camerabody 100.

As illustrated in FIGS. 19A and 19B, the camera body 100 and the firstinterchangeable lens 200 respectively include the camera mount A and thelens mount B each having a contact surface parallel to a directionorthogonal to the optical axis. In a state where the reference surfaceof the camera mount A and that of the lens mount B come into contactwith each other, the camera body 100 and the first interchangeable lens200 can be rotated relative to each other from the mounting-startposition to the mounting-completion position described above.

The state illustrated in FIG. 5B is a state between the mounting-startstate and the mounting-completion state of the camera mount A and thelens mount B described above, and is a state where only the PGNDterminals start being connected to each other prior to connection of theother terminals corresponding to each other, which will be described indetail below.

In this embodiment, a description is given below where the electricalterminals provided on the camera mount are referred to as contact pinsand the electrical terminals provided on the lens mount are referred toas contact faces (or contact pieces). Alternatively, the terminalsprovided on the camera mount may be contact faces, and the terminalsprovided on the lens mount may be contact pins.

The mount portion 1 according to this embodiment is a two-stage(two-step) mount having a height level difference in the optical-axisdirection, as illustrated in FIGS. 4A and 4B and FIGS. 5A to 5C. Asillustrated in FIG. 5A, in the camera mount A of the camera body 100, astage that projects toward the object side is referred to as a cameramount upper stage (second stage), and a stage on the image sensor sideis referred to as a camera mount lower stage (first stage). That is, thecamera mount upper stage projects toward the object side (or the cameraaccessory side) in the optical-axis direction further than the cameramount lower stage.

As illustrated in FIG. 5B, in the lens mount B of the firstinterchangeable lens 200, a stage that is recessed toward the objectside is referred to as a lens mount lower stage (second stage), and astage that projects toward the image sensor side in a state where thelens mount is mounted on the camera mount is referred to as a lens mountupper stage (first stage). That is, in the state where the lens mount ismounted on the camera mount, the lens mount upper stage projects towardthe image capturing apparatus side in the optical-axis direction furtherthan the lens mount lower stage. In this structure, the terminals on thecamera mount upper stage can come into contact with only the terminalson the lens mount lower stage, and the terminals on the camera mountlower stage can come into contact with only the terminals on the lensmount upper stage. In the camera mount A, the camera mount lower stageis located on the near side in the direction of rotation relative to thelens mount B (the accessory mount direction), and the camera mount upperstage is located on the far side. In the lens mount B, the lens mountupper stage is located on the near side in the direction of rotationrelative to the camera mount A (the accessory mount direction), and thelens mount lower stage is located on the far side.

As illustrated in FIG. 5C, the lens mount B rotationally moves (in theright direction in FIG. 5C) relative to the camera mount A while theterminals provided on the lens mount B slide on and come into contactwith the terminals provided on the camera mount A. Then, for example, ina state where the first interchangeable lens 200 is completely mountedon the camera body 100, each of the contact pins of the camera mount Aand a paired (corresponding) one of the contact faces of the lens mountB are electrically connected to each other independently. To simplify adescription given below, a state where a terminal of the camera mount Aand an electrically paired (corresponding) terminal of the lens mount Bare electrically continuous is referred to as connection, and a statewhere terminals that are not electrically paired (not corresponding toeach other) are electrically continuous is referred to as contact.

In this embodiment, a group of a plurality of tabs provided in thecamera mount A and those in the lens mount B are bayonet tabs, and thegroups of tabs engage with each other in the optical-axis direction witha bayonet coupling mechanism, and mounting (coupling) of the mounts iscompleted accordingly.

Now, the order in which the terminals of the mount portion 1 arearranged according to this embodiment is described. As illustrated inFIG. 5A, on the camera mount upper stage, the VDD terminal 1001, theVBAT terminal 1002, the TYPE terminal 1003, and the PGND terminal 1004are arranged sequentially from the far side (trailing end) in the lensmount direction. The far side in the lens mount direction is a side onwhich a terminal of the camera side that comes into contact with aterminal on the lens side last is located in a case of mounting thefirst interchangeable lens 200 on the camera body 100. Therefore, on thelens side, the far side in the lens mount direction is a side on which aterminal of the lens side that comes into contact with a terminal on thecamera side first is located in a case of mounting the firstinterchangeable lens 200 on the camera body 100.

On the camera mount lower stage, the MIF terminal 1005, the DCL terminal1006, the DLC terminal 1007, the LCLK terminal 1008, the DLC2 terminal1009, the DCA terminal 1010, the CS terminal 1011, and the DGND terminal1012 are arranged sequentially from the far side in the lens mountdirection.

Similarly, on the lens mount lower stage, the VDD terminal 2001, theVBAT terminal 2002, the TYPE terminal 2003, and the PGND terminal 2004are arranged sequentially from the far side in the lens mount direction.On the lens mount upper stage, the MIF terminal 2005, the DCL terminal2006, the DLC terminal 2007, the LCLK terminal 2008, the DLC2 terminal2009, the DCA terminal 2010, the CS terminal 2011, and the DGND terminal2012 are arranged sequentially from the far side in the lens mountdirection.

That is, four terminals are disposed on each of the camera mount upperstage and the lens mount lower stage, and eight terminals are disposedon each of the camera mount lower stage and the lens mount upper stage.The number of terminals (exposed contacts) on the camera mount upperstage and on the lens mount lower stage is smaller than the number ofterminals on the camera mount lower stage and the lens mount upperstage.

In a case of rotating the camera mount and the lens mount relative toeach other to mount or dismount the camera accessory on or from theimage capturing apparatus, as in a bayonet coupling mechanism, terminalsprovided on one of the mounts slide on terminals provided on the othermount during mounting or dismounting. In general, on a single plane inthe optical-axis direction, on the camera mount side, the contact pinpresent furthest in the lens mount direction does not slide on contactfaces on the accessory side that do not correspond to the furthestcontact pin when the camera accessory is mounted on or dismounted fromthe image capturing apparatus. On a single plane in the optical-axisdirection, on the lens mount side, the contact face present nearest inthe lens mount direction does not slide on contact pins on the cameraside that do not correspond to the nearest contact face when the cameraaccessory is mounted on or dismounted from the image capturingapparatus. Therefore, a contact pin (first contact pin) of the cameramount which is positioned further in the lens mount direction than theother contact pins (e.g. a contact pin located in the furthest lensmount direction) does not contact other contact surfaces of the lensmount, except for a contact surface of the lens mount which contacts thefirst contact pin when the camera accessory is fully mounted to theimage capturing apparatus. Similarly, a contact surface (first contactsurface) of the camera mount which is positioned nearer in the lensmount direction than the other contact surfaces (e.g. a contact surfacelocated in the nearest lens mount direction) does not contact othercontact pins of the camera mount, except for a contact pin of the cameramount which contacts the first contact surface when the camera accessoryis fully mounted to the image capturing apparatus.

However, terminals other than the above-described terminals wear out asthe number of times the lens mount is mounted on and dismounted from thecamera mount increases. Specifically, the terminals (contact pins) ofthe camera mount are movable pins that can be advanced and retreated(projected and retracted) in a direction parallel to the optical-axis,and slide on the terminals (contact faces) of the lens mount at a tippoint thereof. Therefore, the contact pins need to be made increasinglydurable to sliding.

The above-described issue becomes more noticeable as the number ofterminals disposed in a line on a single plane orthogonal to the opticalaxis increases, and the number of times the contact pins slide on thecontact faces increases. As the contact pins and the contact faces wearout, the contact impedance of the terminals increases, and the voltagesignificantly drops to a level lower than the allowable operatingvoltage range of an electric circuit. As a result, for example, amalfunction of the interchangeable lens may occur.

Accordingly, in this embodiment, in order to decrease the number oftimes terminals slide on other terminals, the terminals are held atdifferent positions in the optical-axis direction, namely, on the twostages including the upper stage and the lower stage, and the contactpins on the camera side come into contact with the contact faces on theinterchangeable lens side at different heights depending on whether thestage is the upper stage or the lower stage. With this structure, foreach stage that holds the terminals, wearing out of the terminals can bereduced.

Further, in this embodiment, for each mount, the number of terminalsheld on the upper stage is different from the number of terminals heldon the lower stage. Therefore, for example, when terminals of highimportance among the plurality of terminals are disposed on the stagehaving a smaller number of terminals, wearing out of the importantterminals can be reduced. Specifically, on each of the camera mountupper stage and the lens mount lower stage having a smaller number ofterminals, the power-supply-system terminals (the VDD terminal, the VBATterminal, and the PGND terminal), which are signal terminals in which anincrease in the contact impedance is to be suppressed to the largestextent possible, are arranged. On each of the camera mount lower stageand the lens mount upper stage, terminals that are used mainly incommunication and are less likely to be affected by an increase in theimpedance (than the power-supply-system terminals) are arranged. Thisstructure enables stable power supply to the accessory and contributesto stable operations (for example, focus control) of the cameraaccessory.

The DGND terminal 1012 of the camera mount A is located on the cameramount lower stage and disposed nearest (leading end) in the lens mountdirection, and therefore, is located at the most disadvantageouslocation in terms of durability to sliding of the contact pins on thecamera side. However, in order to protect an electric circuit and anelement provided in the camera accessory from, for example, staticelectricity, the DGND terminal needs to physically connect a metalportion formed in the camera mount to ground. In this embodiment, theDGND terminal is arranged nearest in the lens mount direction so as tofacilitate processing performed for the above-described reason.

This embodiment assumes a system in which the level of the value of acurrent provided to the DGND terminal is lower than that for the PGNDterminal. Therefore, in this embodiment, the PGND terminal, for whichthe level of the value of a current provided to the terminal is higher,is disposed on the camera mount upper stage (and on the lens mount lowerstage) on which a smaller number of terminals are disposed and which isadvantageous in terms of reducing an increase in the contact impedance.

In the camera mount A according to this embodiment, the twopower-supply-system contact pins (the VDD terminal 1001 and the VBATterminal 1002) are disposed on the camera mount upper stage as the firstand second terminals when viewed from the far side in the lens mountdirection, and the TYPE terminal 1003 is disposed adjacent to thepower-supply-system terminals. In the lens mount B according to thisembodiment, the two power-supply-system contact faces (the VDD terminal2001 and the VBAT terminal 2002) are disposed on the lens mount lowerstage as the first and second terminals when viewed from the far side inthe lens mount direction, and the TYPE terminal 2003 is disposedadjacent to the power-supply-system terminals.

With the above-described structure, in the mount portion 1 according tothis embodiment, the two power-supply-system terminals (the VDD terminaland the VBAT terminal) are not adjacent to the PGND terminal. Therefore,the possibility of an inter-terminal short circuit between the PGNDterminal and the two power-supply-system terminals can be reduced, and amalfunction or a failure in a power supply circuit provided on thecamera side due to the short circuit can be prevented.

When the TYPE terminal 1003 arranged between the VBAT terminal 1002 andthe PGND terminal 1004 is provided with a protective element on thesignal line of the TYPE terminal 1003, an electric circuit of the camerabody 100 can be protected.

As in the TYPE terminal 1003, when a protective element is added to thesignal line of a terminal other than the TYPE terminal, the measuretaken for the TYPE terminal can be similarly taken. However, the DCLterminal, the DLC terminal, the LCLK terminal, the DLC2 terminal, theDCA terminal, and the CS terminal are terminals for communication asdescribed above, and addition of a protective element leads to anincrease in the wiring capacitance. In this case, an increase in thewiring capacitance may affect communication and, for example, theresponsiveness of a rise or a fall of the communication waveform may becompromised. Therefore, it is desirable to provide no protective elementin the communication terminals to the extent possible.

In the mount portion 1 according to this embodiment, the signal voltageof the TYPE terminal 1003 is constant, and the signal value does notchange in a period during which, for example, the first interchangeablelens 200 is mounted on the camera body 100. Therefore, even if aprotective element is added to the TYPE terminal 1003 as in the mountportion 1 according to this embodiment, operations performed by thecamera body 100 and the first interchangeable lens 200 are lessaffected.

The signal voltage of the MIF terminal 1005 is constant similarly to theTYPE terminal 1003, and therefore, may include a protective element asin the TYPE terminal 1003. However, in the mount portion 1 according tothis embodiment, the MIF terminal 1005 is not arranged adjacent to thepower-supply-system terminals. The reasons for this will be describedbelow.

As illustrated in FIG. 5C, in the camera mount A and in the lens mountB, the inter-terminal pitch W2 (distance) between the VDD terminal andthe VBAT terminal is set to a pitch wider than the basic pitch W1(W2>W1). In the camera mount A and in the lens mount B, the MIF terminaland the PGND terminal are held on different stages of the mount in theoptical-axis direction, and the inter-terminal pitch W3 is set to apitch wider than the basic pitch W1 and the pitch W2 (W3>W2>W1). Aninter-terminal pitch is assumed to be the distance between the centerpoints (center lines) of terminals (contact pins or contact faces) inthe mount direction (rotation direction) of the lens mount B; however,an inter-terminal pitch may be the distance between conductive portions(between metal regions) provided in terminals. In a case where the lensmount B is mounted on the camera mount A, the distance between thelocation of contact of terminals, namely, a contact pin and acorresponding contact face (connection point) and the location ofcontact of the adjacent terminals may be assumed to be theinter-terminal pitch.

In this embodiment, the description has been given while assuming a casewhere the width of the contact face of the VDD terminal 2001 and theVBAT terminal 2002 in the circumferential direction of the lens mount Bis a basic width described below; however, the width is not limited tothis. For example, the width of the contact face of the VDD terminal2001 and the VBAT terminal 2002 may be set to a width wider than thebasic width or narrower than the basic width. In this case, the pitchbetween the VDD terminal and the VBAT terminal needs to be set by takinginto consideration the difference between the basic width and the widthof the VDD terminal 2001 and the VBAT terminal 2002. For example, in acase where the width of the VDD terminal 2001 and the VBAT terminal 2002is wider than the basic width in the lens removal direction, the pitchbetween the VDD terminal and the VBAT terminal needs to be made wider bythe difference from the basic width described above.

The basic pitch described above is the distance between terminals thatis set by taking into consideration looseness and a tolerance relatingto manufacturing and assembling of the camera body 100. One contact faceof the lens mount B for which the basic width described below is setdoes not simultaneously come into contact with a plurality of contactpins of the camera mount A for which the basic pitch is set as long as acontact pin is not deformed, namely, for example, is not bent, or aconductive foreign object is not present between terminals. Therefore, ashort circuit between adjacent terminals that occurs when a contact pinof the camera mount A comes into contact with a contact face of the lensmount B at two or more locations can be prevented. A description isgiven below under the assumption that the pitch between a contact pinnot otherwise specified and an adjacent terminal is set to the basicpitch.

The basic width described above is the width of the contact faces of thelens mount B that is set by taking into consideration looseness and atolerance relating to manufacturing and assembling of the cameraaccessory. The width of the contact faces is the width of the contactfaces in the mount direction (rotation direction) of the lens mount B.As described above, a plurality of contact pins for which the basicpitch is set in the camera mount A do not simultaneously come intocontact with one contact face for which the basic width is set. In astate where a camera accessory is mounted, a contact pin of the imagecapturing apparatus does not come off from a contact face of the cameraaccessory, namely, the lens mount B, for which the basic width is set aslong as the contact pin on the camera side is deformed or, for example,a conductive foreign object is present between contact pins. Adescription is given below under the assumption that the width of acontact face not otherwise specified is set to the basic width.

The inter-terminal pitch between the VDD terminal 1001 and the VBATterminal 1002 on the camera side according to this embodiment is set soas to be wider than the width of the VDD terminal 2001 and the VBATterminal 2002 on the accessory side for which the basic width is set byapproximately 3° by taking into consideration reduction in the size ofthe unit and safety of the power supply. With this structure, even in acase where the VDD terminal or the VBAT terminal on the camera side isdeformed or a conductive foreign object is present between theterminals, the possibility of the VDD terminal on the accessory sidecoming into contact with the above-described two terminalssimultaneously can be reduced, and therefore, the possibility of a shortcircuit between the adjacent terminals can be reduced.

In this embodiment, the description has been given while assuming a casewhere the inter-terminal pitch between the VDD terminal 1001 and theVBAT terminal 1002 in the circumferential direction of the camera mountA is set to a pitch wider than the basic pitch by 3°; however, the pitchis not limited to this. In this embodiment, the inter-terminal pitchneeds to be at least made wider in the direction of relative rotation ofthe camera mount A and the lens mount B.

In the mount portion 1 according to this embodiment, the PGND terminal1004 is disposed nearest in the lens mount direction on the camera mountupper stage, and the PGND terminal 2004 is disposed nearest in the lensmount direction on the lens mount lower stage.

The PGND terminal 2004 on the lens mount B is a contact face having awidth wider than the basic width described above and is a terminalhaving a contact face having the widest width among the plurality ofterminals provided on the lens mount B. In this embodiment, the width ofa contact face described above is the width of the contact face in adirection (removal direction) in which the lens mount B is dismountedfrom the camera mount A while assuming a location (connection point) atwhich corresponding terminals are electrically connected to each otheras a reference. The removal direction is synonymous with the near sidein the mount direction of the lens mount B. The width of a contact facemay be defined as the width of the contact face in the direction(removal direction) in which the lens mount B is dismounted from thecamera mount A while the center of the contact face in thecircumferential direction of the mount is simply assumed to be areference.

In this structure, the PGND terminal 2004 is a terminal that iselectrically connected to a corresponding terminal first among all ofthe terminals when the first interchangeable lens 200 is mounted on thecamera body 100. The PGND terminal 2004 is a terminal that iselectrically disconnected from the corresponding terminal last among allof the terminals when the first interchangeable lens 200 is dismounted(removed) from the camera body 100.

For example, a case is assumed where the PGND terminal is disposedfurther than the power-supply-system terminals (the VDD terminal and theVBAT terminal) in the lens mount direction. In this case, for example,when the first interchangeable lens 200 is removed from the camera body100, the PGND terminal of the lens mount may slide on thepower-supply-system terminals of the camera mount. In this case, thePGND terminal of the lens mount may instantaneously come into contactwith the power-supply-system terminals of the camera mount depending onthe speed at which the first interchangeable lens 200 is rotated in theremoval direction. As a result, due to the above-described issue, theoutput of a camera power supply unit 103 described below of the camerabody 100 connected to the power-supply-system terminals may beshort-circuited, and a malfunction relating to power supply or amalfunction in power supply control may occur.

For example, a configuration is assumed where the PGND terminal isdisconnected from the contact face on the lens mount side prior todisconnection of the other terminals. In this case, when the PGNDterminals are disconnected from each other in a specific state where thepower-supply-system terminals of the camera mount A are not disconnectedfrom the power-supply-system terminals of the lens mount B and wherepower is kept supplied from the camera body 100, a malfunction or afailure may occur in both the devices.

For the above-described issue, in the mount portion 1 according to thisembodiment, when the first interchangeable lens 200 is mounted on anddismounted from the camera body 100, the PGND terminal 2004 of the lensmount B does not slide on (does not come into contact with) anyterminals other than the PGND terminal 1004 of the camera mount A. Withthis structure, the power-supply-system terminals (the VDD terminal andthe VBAT terminal) of the camera mount A do not instantaneously comeinto contact with the PGND terminal 2004 of the lens mount B.Accordingly, the possibility of a short circuit between the terminalscan be reduced.

In the mount portion 1 according to this embodiment, among all of theterminals described above, the PGND terminals of the respective mountsare connected to each other first when the camera accessory is mountedon the camera and disconnected from each other last when the cameraaccessory is removed from the camera. In other words, when the cameraaccessory is detached (removed) from the camera, in the mount portion 1,the PGND terminal of the camera mount is kept connected to the PGNDterminal of the lens mount until corresponding terminals other than thePGND terminals are disconnected from each other. With this structure, inthe camera mount A and in the lens mount B, ground floating in which thePGND terminals are disconnected from each other in a state where poweris kept supplied can be avoided, and the possibility of a malfunction ora failure can be reduced in both the devices.

As illustrated in FIG. 5C, the inter-terminal pitch between the PGNDterminal 1004 and the adjacent terminal, namely, the TYPE terminal 1003,in the camera mount A (and that in the lens mount B) is wider than theabove-described basic pitch (W2>W1). Specifically, the inter-terminalpitch between the PGND terminal 1004 and the TYPE terminal 1003 is madewider than the basic pitch by an amount substantially equal to theamount by which the width of the contact face of the PGND terminal 2004is made wider in the direction (removal direction) in which the lensmount B is dismounted. With this structure, the possibility of the PGNDterminal 2004 coming into contact with the PGND terminal 1004 and theTYPE terminal 1003 simultaneously due to the PGND terminal 2004 of thelens mount B having a width wider than the basic width can be reduced,and the possibility of a short circuit between the adjacent terminalscan be reduced.

As illustrated in FIGS. 5A to 5C, in the mount portion 1 according tothis embodiment, the MIF terminal 1005 is disposed furthest in the lensmount direction on the camera mount lower stage, and the MIF terminal2005 is disposed furthest in the lens mount direction on the lens mountupper stage. With this structure, wearing out of the MIF terminals,which are terminals for detecting the state of mounting of the lensmount B on the camera mount A and which are important terminals servingas a trigger for starting and ending communication between the cameraand the camera accessory, can be reduced.

The MIF terminal 2005 of the lens mount B has a contact face having awidth narrower than the contact faces having the basic width describedabove in the relative rotation direction of the lens mount B.Specifically, in the lens mount B according to this embodiment, thewidth of the MIF terminal 2005 is made narrower (shorter) than the basicwidth by approximately 1° so that the order in which the above-describedterminals are connected to each other does not change even if loosenessand a tolerance relating to manufacturing and assembling are taken intoconsideration. With this structure, the MIF terminals are connected toeach other last among all of the above-described terminals included inthe mount portion 1 when the camera accessory is mounted on the camera,and are disconnected from each other first when the camera accessory isremoved from the camera.

Accordingly, in the mount portion 1 according to this embodiment, in astate where the lens mount B is not completely mounted on the cameramount A, the camera does not erroneously detect mounting of the cameraaccessory. With this structure, for example, in a state where thepower-supply-system terminals are not connected to each other, erroneousdetection of mounting of the camera accessory can be suppressed, and thepossibility of a malfunction of the camera before power is supplied fromthe camera to the camera accessory can be reduced.

As illustrated in FIGS. 5A to 5C, in the camera mount A according tothis embodiment, the DGND terminal 1012 is disposed nearest in the lensmount direction on the camera accessory lower stage, and the CS terminal1011 is disposed adjacent to the DGND terminal 1012. In the lens mount Baccording to this embodiment, the DGND terminal 2012 is disposed nearestin the lens mount direction on the lens mount upper stage, and the CSterminal 2011 is disposed adjacent to the DGND terminal 2012. Thedetails of the arrangement of the CS terminals will be described below.As described above, the DGND terminal is disposed nearest in the lensmount direction by taking into consideration easy processing forphysically connecting a metal portion of the mount to ground.

As illustrated in FIGS. 5A to 5C, in the mount portion 1 according tothis embodiment, the group of terminals (the LCLK terminal, the DCLterminal, and the DLC terminal) of the first communication unit isdisposed adjacent to the MIF terminal. In the mount portion 1 accordingto this embodiment, the group of terminals corresponding to the firstcommunication unit is disposed further in the lens mount direction thanthe group of terminals of the second and third communication units.

With this structure, on the camera mount lower stage and the lens mountupper stage, wearing out of the terminals corresponding to the firstcommunication unit can be reduced to the largest degree next to the MIFterminal 1005. With the above-described structure, wearing out of thegroup of terminals corresponding to the first communication unit, whichperforms specifically important first communication among the types ofcommunication performed between the camera and the lens, can be reducedto a larger degree than the other communication terminals.

As illustrated in FIGS. 5A to 5C, in the mount portion 1 according tothis embodiment, the DLC2 terminal 1009 is disposed adjacent to thegroup of terminals corresponding to the first communication unit on thecamera mount lower stage. In the mount portion 1 according to thisembodiment, the DLC2 terminal 2009 is disposed adjacent to the group ofterminals corresponding to the first communication unit on the lensmount upper stage. The details will be described below.

Configuration of Adaptor 400

Now, a case where the second interchangeable lens 300 is mounted on thecamera body 100 with the adaptor 400 therebetween is described withreference to FIG. 6. FIG. 6 is a block diagram illustrating a statewhere the second interchangeable lens 300 is mounted on the camera body100 with the adaptor 400 therebetween. As illustrated in FIG. 6, a mountof the adaptor 400 and the mount of the second interchangeable lens 300are collectively referred to as a mount portion 2.

The adaptor 400 includes the lens mount B, which is the same as that ofthe first interchangeable lens 200 described above, on a side to whichthe camera body 100 is coupled. The adaptor 400 includes the cameramount C, which corresponds to the lens mount D provided in the secondinterchangeable lens 300, on a side opposite the lens mount B. FIGS. 7Aand 7B are diagrams illustrating the camera mount C and the lens mountD. FIG. 7A is a front view of the camera mount C provided in the adaptor400, and FIG. 7B is a front view of the lens mount D provided in thesecond interchangeable lens 300. The details of terminals included inthe camera mount C and in the lens mount D will be described below.

The adaptor 400 is a camera accessory including an adaptor operationinput unit 402, which receives user operations, an adaptor power supplyunit 403 (see FIGS. 8A and 8B) for the adaptor 400, and an adaptorcontroller 401, which includes a central processing unit (CPU) thatcentrally controls operations of the adaptor 400. For example, theadaptor controller 401 controls communication between the adaptorcontroller 401 and the camera controller 101 via the mount portion 1 oraccepts operation input to the adaptor operation input unit 402. In thisembodiment, the adaptor 400 is used to mount, for example, the secondinterchangeable lens 300, which has a flange focal length notcorresponding to the camera body 100, indirectly on the camera body 100.

The second interchangeable lens 300 includes a lens 19, which isconstituted by optical members including a focus lens, a zoom lens, adiaphragm, and an image stabilizing lens not illustrated, and a lensdrive unit 20, which drives an actuator that moves or operates theoptical members of the lens 19. The second interchangeable lens 300further includes a second lens controller 301, which includes a CPU thatcontrols communication between the second lens controller 301 and thecamera controller 101 via the mount portion 1 and via the mount portion2 or performs control for driving the lens drive unit 20.

Now, connection between the camera body 100 and the secondinterchangeable lens 300 with the adaptor 400 therebetween is describedwith reference to FIGS. 8A and 8B. FIGS. 8A and 8B are diagramsillustrating the state of connection between mounts in a case ofmounting the second interchangeable lens 300 on the camera body 100 withthe adaptor 400 therebetween. The configuration of the terminals in themount portion 1 is as described above, and therefore, a descriptionthereof will be omitted. In this embodiment, the DLC2 terminal need notbe provided on a side of the adaptor 400 close to the secondinterchangeable lens 300 (in the camera mount C).

As illustrated in FIGS. 8A and 8B, the mount portion 2 includes aplurality of terminals that enable electrical connection between theadaptor 400 and the second interchangeable lens 300. The plurality ofterminals in the camera mount C are exposed outside the adaptor 400 as aplurality of electrical contact pins provided on a contact holdingmember 405 (see FIG. 7A), which corresponds to a terminal holder. Theplurality of terminals in the lens mount D are exposed outside thesecond interchangeable lens 300 as a plurality of electrical contactfaces provided on a contact face holding member 305 (see FIG. 7B), whichcorresponds to a terminal holder. In a state where the secondinterchangeable lens 300 is mounted on the adaptor 400, which is mountedon the camera body 100, each contact among the contact pins describedabove is electrically connected to a corresponding contact among thecontact faces described above.

The functions of the terminals that are common to the camera mount C andthe lens mount D are described below. VDD terminals 3001 and 4001 arepower supply terminals for supplying communication control power (VDD),which is communication power used mainly in communication control, fromthe camera body 100 to the second interchangeable lens 300 via theadaptor 400. The voltage of the power to be supplied to each cameraaccessory from the camera body 100 is set to 5.0 V.

VBAT terminals 3002 and 4002 are power supply terminals for supplyingdriving power (VBAT), which is driving power used in operations of amechanical drive unit mainly including an actuator, such as a motor,from the camera body 100 to the second interchangeable lens 300. Thevoltage of the power to be supplied to each camera accessory from thecamera body 100 is set to 4.5 V. The VDD terminals and the VBATterminals described above are power-supply-system terminals forsupplying power from the camera body 100 to a camera accessory.

DGND terminal 3012 and 4012 are ground terminals (GND terminals)corresponding to the communication control power VDD. The DGND terminals3012 and 4012 also connect a circuit provided within the adaptor 400 toground.

PGND terminals 3004 and 4004 are ground terminals for connecting thecamera body 100 and a mechanical drive system including a motor(actuator) provided in the second interchangeable lens 300 to ground.That is, the PGND terminals are ground terminals (GND terminals)corresponding to the driving power VBAT.

MIF terminals 3005 and 4005 are terminals for detecting mounting of thesecond interchangeable lens 300 on the camera body 100. The cameracontroller 101 detects a voltage level indicated by the MIF terminals todetect mounting or removal of a camera accessory on or from the camerabody 100. After the camera controller 101 has detected, for example,mounting of a camera accessory as a result of the detection, the cameracontroller 101 performs control to start supplying power to thepower-supply-system terminals and to start communication between thecamera body 100 and the second interchangeable lens 300 via the adaptor400.

Now, terminals for various types of communication between the adaptor400 and the second interchangeable lens 300 are described. Unlike thefirst interchangeable lens 200 described above, the secondinterchangeable lens 300 includes only terminals corresponding to thefirst communication unit as an independent communication system.

LCLK terminals 3008 and 4008 are terminals of the first communicationunit. The LCLK terminals 3008 and 4008 are terminals for a communicationclock signal output from the camera body 100 to the secondinterchangeable lens 300 and are terminals for the camera body 100 tomonitor the busy state of the second interchangeable lens 300.

DCL terminals 3006 and 4006 are terminals of the first communicationunit and are communication data terminals for two-way communicationbetween the camera body 100 and the second interchangeable lens 300. TheDCL terminals 3006 and 4006 are CMOS-output-type interfaces. The CMOSoutput type in this embodiment is a type in which switch output ispresent for both H (High) and L (Low) indicated by a voltage. The opentype described below is a type in which switch output is present on onlythe L side.

DLC terminals 3007 and 4007 are terminals of the first communicationunit and are terminals for communication data output from the secondinterchangeable lens 300 to the camera body 100. The DLC terminals 3007and 4007 are CMOS-type interfaces.

In the adaptor 400, the VDD terminal, the VBAT terminal, the DGNDterminal, the PGND terminal, the MIF terminal, the LCLK terminal, theDCL terminal, and the DLC terminal in the mount portion 1 areelectrically connected to those in the mount portion 2.

Connection, in the adaptor 400, of terminals not provided in the mountportion 2 is described below. The TYPE terminals 1003 and 2003 providedin the mount portion 1 are pull-down connected to the DGND terminal witha predetermined resistance described below in the adaptor 400.

The DLC2 terminals are terminals that correspond to the secondcommunication unit as described above; however, the DLC2 terminals arenot used as communication terminals in a case where the secondinterchangeable lens 300 is mounted on the camera body 100 with theadaptor 400 therebetween. Therefore, the DLC2 terminals 1009 and 2009are pull-down connected to the DGND terminal with a predeterminedresistance in the adaptor 400 as termination processing.

The DCA terminals are terminals that correspond to the thirdcommunication unit. In the mount portion 1, the DCA terminals arecommunication data terminals for two-way communication between thecamera body 100 and the adaptor 400 and are CMOS-type interfaces. In themounts of the adaptor 400, the DCA terminal in the mount portion 1 isnot connected to a terminal in the mount portion 2.

The CS terminals are terminals that correspond to the thirdcommunication unit as described above and are signal terminals forrequesting communication between the camera body 100 and the adaptor400. The CS terminals are open-type interfaces. In the mounts of theadaptor 400, the CS terminal in the mount portion 1 is not connected toa terminal in the mount portion 2.

In a case where the second interchangeable lens 300 is mounted on thecamera body 100 with the adaptor 400 therebetween, the communicationvoltage at the terminals corresponding to the first communication unitis set to a voltage equal to that of VDD, and the communication voltageat the terminals corresponding to the second and third communicationunits is set to approximately 3.0 V. That is, in the case where thesecond interchangeable lens 300 is mounted on the camera body 100 withthe adaptor 400 therebetween, the communication voltage at the firstcommunication unit is different from the communication voltage at thesecond and third communication units.

Configuration of Intermediate Accessory 500

Now, a case where the first interchangeable lens 200 is mounted on thecamera body 100 with the intermediate accessory 500 therebetween isdescribed with reference to FIG. 9 and FIGS. 10A and 10B. FIG. 9 is ablock diagram illustrating a state where the first interchangeable lens200 is mounted on the camera body 100 with the intermediate accessory500 therebetween according to this embodiment. As illustrated in FIG. 9,a mount of the intermediate accessory 500 and the mount of the firstinterchangeable lens 200 are collectively referred to as a mount portion3.

The intermediate accessory 500 includes the lens mount B, which is thesame as that of the first interchangeable lens 200 described above, on aside to which the camera body 100 is coupled. The intermediate accessory500 includes the camera mount A, which is the same as that of the camerabody 100, on a side opposite the lens mount B. These mounts are the sameas that of the camera body 100 and that of the first interchangeablelens 200, and therefore, detailed descriptions thereof will be omitted.

The intermediate accessory 500 is a camera accessory including anaccessory operation input unit 502, which receives user operations, anaccessory power supply unit 503 for the intermediate accessory 500, andan accessory controller 501, which includes a CPU that centrallycontrols operations of the intermediate accessory 500. For example, theaccessory controller 501 controls communication between the accessorycontroller 501 and the camera controller 101 via the mount portion 1 oraccepts operation input to the accessory operation input unit 502. Inthis embodiment, the intermediate accessory 500 is a camera accessoryfor adding functions of an extender that includes a group of lenses (notillustrated) for enlargement or magnification variation or adding somecamera functions as operations of both the camera body 100 and the firstinterchangeable lens 200.

Now, connection between the camera body 100 and the firstinterchangeable lens 200 with the intermediate accessory 500therebetween is described with reference to FIGS. 10A and 10B. FIGS. 10Aand 10B are diagrams illustrating the state of connection between mountsin a case of mounting the first interchangeable lens 200 on the camerabody 100 with the intermediate accessory 500 therebetween. Theconfiguration of the terminals in the mount portion 1 is as describedabove, and therefore, a description thereof will be omitted.

As illustrated in FIGS. 10A and 10B, the mount portion 3 includes aplurality of terminals that enable electrical connection between theintermediate accessory 500 and the first interchangeable lens 200.Contact pins that are exposed outside the intermediate accessory 500 asterminals are the same as the contact pins of the camera body 100described above.

The features of the intermediate accessory 500 for the camera body 100and the first interchangeable lens 200 described above are describedbelow. As illustrated in FIGS. 10A and 10B, the intermediate accessory500 can be connected to the camera body 100 and to the firstinterchangeable lens 200 via a terminal group provided in the camerabody 100 and that provided in the first interchangeable lens 200.

Between the VDD terminal 1001 and the VDD terminal 2001 of theintermediate accessory 500, an inter-terminal through-wiring line islaid from the mount portion 1 to the mount portion 3. To an electriccircuit in the intermediate accessory 500, VDD (communication controlpower) can be supplied.

Between the DGND terminal 1012 and the DGND terminal 2012 of theintermediate accessory 500, an inter-terminal through-wiring line islaid from the mount portion 1 to the mount portion 3. An electriccircuit in the intermediate accessory 500 can be grounded to the DGNDterminal.

The DCA terminals 1010 and 2010 of the intermediate accessory 500 areterminals that correspond to the third communication unit describedabove and are communication data terminals for two-way communicationamong the camera body 100, the first interchangeable lens 200, and theintermediate accessory 500. The CS terminals 1011 and 2011 of theintermediate accessory 500 are terminals that correspond to the thirdcommunication unit described above and are signal terminals forrequesting communication among the camera body 100, the firstinterchangeable lens 200, and the intermediate accessory 500.

Although specific descriptions are not given of the VBAT terminals, thePGND terminals, the MIF terminals, the TYPE terminals, the LCLKterminals, the DCL terminals, the DLC terminals, and the DLC2 terminalsof the intermediate accessory 500, between the terminals of each typedescribed above, an inter-terminal through-wiring line is laid from themount portion 1 to the mount portion 3.

Here, in a case where the first interchangeable lens 200 is mounted onthe camera body 100 with the intermediate accessory 500 therebetween,the communication voltage at the terminals of the first, second, andthird communication units are set to approximately 3.0 V as in the caseof mounting the first interchangeable lens 200 directly on the camerabody 100.

Terminal Processing for Signal Line of Each Communication Terminal

Now, terminal processing for the signal line of each communicationterminal is described with reference to FIG. 3, FIGS. 8A and 8B, andFIGS. 10A and 10B. In the camera mount A, a signal line that correspondsto the LCLK terminal is pull-up connected to an electric potentialidentical to the communication voltage of the terminals corresponding tothe first communication unit via a resistor R_LCLK_C 120, whichindicates a predetermined resistance in the camera mount A. In the lensmount B, a signal line that corresponds to the LCLK terminal is pull-upconnected to an electric potential identical to the communicationvoltage of the terminals corresponding to the first communication unitvia a resistor R_LCLK_L 220, which indicates a predetermined resistancein the lens mount B.

In the lens mount B, a signal line that corresponds to the DCL terminalis pull-up connected to an electric potential identical to thecommunication voltage of the terminals of the first communication unitvia a resistor R_DCL_L 221, which indicates a predetermined resistancein the lens mount B.

In the camera mount A, a signal line that corresponds to the DLCterminal is pull-up connected to an electric potential identical to thecommunication voltage of the terminals of the first communication unitvia a resistor R_DLC_C 121, which indicates a predetermined resistancein the camera mount A.

In the camera mount A, a signal line that corresponds to the DLC2terminal is pull-down connected to the signal line of the DGND terminalvia a resistor R_DLC2_C 122, which indicates a predetermined resistancein the camera mount A. In the adaptor 400, a signal line thatcorresponds to the DLC2 terminal is pull-down connected to the signalline of the DGND terminal via a resistor R_DLC2_A 422, which indicates apredetermined resistance in the adaptor 400.

In the camera mount A, a signal line that corresponds to the CS terminalis pull-up connected to an electric potential identical to thecommunication voltage of the terminals of the third communication unitvia a resistor R_CS_C 123, which indicates a predetermined resistance inthe camera mount A. In the lens mount B, the signal line of the CSterminal is pull-up connected to an electric potential identical to thecommunication voltage of the terminals corresponding to the thirdcommunication unit via a resistor R_CS_L 222, which indicates apredetermined resistance in the lens mount B. The signal line of the CSterminal in the adaptor 400 and that in the intermediate accessory 500are pull-up connected to an electric potential identical to thecommunication voltage of the terminals corresponding to the thirdcommunication unit via a resistor R_CS_A 420 and via a resistor R_CS_A520 respectively, the resistor R_CS_A 420 and the resistor R_CS_A 520each indicating a predetermined resistance in the corresponding device.

In the camera mount A, the signal line of the DCA terminal is pull-upconnected to an electric potential identical to the communicationvoltage of the terminals corresponding to the third communication unitvia a resistor R_DCA_C 124, which indicates a predetermined resistancein the camera mount A.

Configurations of Communication Interface Units in Camera Body 100

Now, the configuration of a first communication I/F unit 102 a and thatof a second/third communication I/F unit 102 b, which function asinterface circuits between the communication terminals provided in thecamera body 100 and the camera controller 101, are described withreference to FIG. 3 and FIGS. 8A and 8B.

As illustrated in FIG. 3 and FIGS. 8A and 8B, the first communicationI/F unit 102 a is provided within the camera body 100. The firstcommunication I/F unit 102 a is connected to the DCL terminal, the DLCterminal, and the LCLK terminal and functions as an interface circuitfor first communication performed between the camera body 100 and eachinterchangeable lens.

The second/third communication I/F unit 102 b is provided within thecamera body 100. The second/third communication I/F unit 102 b isconnected to the DLC2 terminal, the DCA terminal, and the CS terminaland functions as an interface circuit for second communication and thirdcommunication performed between the camera body 100 and eachinterchangeable lens. Hereinafter, the first communication I/F unit 102a and the second/third communication I/F unit 102 b are collectivelyreferred to as an I/F unit 102. In this embodiment, a description isgiven of an example case where the camera controller 101 is driven at avoltage level of 3.3 V and where the voltage level of the cameracontroller 101 is 3.3 V, as illustrated in FIG. 3 and FIGS. 8A and 8B;however, the voltage level may be set to another value.

The I/F unit 102 has a level shifter function for conversion between avoltage indicated by the terminals provided in the camera mount A andthe voltage of the camera controller 101 as one of the main functionsthereof. The level shifter function is as follows. For example, in acase where the first interchangeable lens 200 is mounted on the camerabody 100, the interface voltage of the terminals corresponding to thefirst, second, and third communication units is 3.0 V, as describedabove. However, a voltage indicated by the camera controller 101 is 3.3V, and therefore, the voltage indicated by the terminals differs fromthat indicated by the camera controller 101. The I/F unit 102 performsvoltage conversion for the voltage indicated by the terminals to adjustthe difference.

For example, in a case where the second interchangeable lens 300 ismounted on the camera body 100 with the adaptor 400 therebetween, theinterface voltage of the terminals that correspond to the firstcommunication unit is equal to the voltage of VDD (5.0 V). The interfacevoltage of the terminals that correspond to the second and thirdcommunication units is 3.0 V. Also in this case, the I/F unit 102performs voltage conversion for the voltage indicated by the terminalsto adjust the difference in voltage between the camera controller 101and the terminals. That is, the I/F unit 102 performs voltage conversionfor signals of the terminals by applying a power voltage (3.3 V)indicating a voltage level equal to the voltage of the camera controller101 and a power voltage (5.0 V or 3.0 V) at a voltage level equal to thevoltage indicated by the terminals.

Regarding the second/third communication I/F unit 102 b, the voltagelevel indicated by the terminals provided in the mount has a fixed valueat all times. Therefore, if the fixed value is at a voltage level equalto the voltage of the camera controller 101, the second/thirdcommunication I/F unit 102 b need not have the level shifter functiondescribed above.

The I/F unit 102 has a function of switching the LCLK terminal 1008 andthe DCL terminal 1006 between open-drain-type output andCMOS-output-type output in the camera mount A as one of the mainfunctions thereof, which is specifically described in detail below.

For example, in an initial state immediately after the firstinterchangeable lens 200 has been mounted on the camera body 100, theLCLK terminal 1008 and the DCL terminal 1006 of the camera body 100perform open-drain-type output. The camera controller 101 monitors thevoltage level of the LCLK terminal 1008 via a BUSY input terminal of thecamera controller 101, as illustrated in, for example, FIG. 3. Forexample, in a case where communication with the first interchangeablelens 200 is not possible, the camera controller 101 outputs a Low-levelvoltage to the LCLK terminal 2008 in the lens mount B. In a case wherecommunication is possible, the camera controller 101 switches the LCLKterminal 2008 to the input side. At this time, to the LCLK terminal linein each mount, a High-level voltage is output from the resistor R_LCLK_C120 and from the resistor R_LCLK_L 220, which are pull-up resistors.

When the camera controller 101 detects, for example, switching of thevoltage level of the LCLK terminal 1008 to the High level, the cameracontroller 101 recognizes that communication with the firstinterchangeable lens 200 becomes possible. Thereafter, the cameracontroller 101 selects the open drain type or the CMOS output type to beapplied to the LCLK terminal 1008 and the DCL terminal 1006, and makes achange to the selected output type via the I/F unit 102. Here,communication in a case of using the I/F unit 102 in accordance with theopen drain type is referred to as open drain communication, andcommunication in a case of using the I/F unit 102 in accordance with theCMOS output type is referred to as CMOS communication.

In a case where a High-level voltage is detected from the LCLK terminal1008 when the first interchangeable lens 200 is mounted, the cameracontroller 101 switches the LCLK terminal 1008 and the DCL terminal 1006to the CMOS output type and performs CMOS communication with the firstinterchangeable lens 200. When the second interchangeable lens 300 ismounted, the camera controller 101 keeps the LCLK terminal 1008 and theDCL terminal 1006 to be of the open drain type and performs open draincommunication with the second interchangeable lens 300. Thereafter, whenthe camera controller 101 determines that the second interchangeablelens 300 is an interchangeable lens supporting CMOS communication, thecamera controller 101 uses the I/F unit 102 to switch the LCLK terminal1008 and the DCL terminal 1006 to the CMOS output type and performs CMOScommunication with the lens.

The open-type output system described above need not be an open drainoutput system and may be an open collector output system. Output of theHigh-level voltage may be implemented by providing the pull-up resistorsas described above. The switching method of the output system need notbe limited to the method described above. When an interchangeable lensis mounted on the camera body 100, the LCLK terminal 1008 and the DCLterminal 1006 at least need to perform open-type communication.

The I/F unit 102 has an input/output direction switch function forswitching the input/output direction for the DCL terminal 1006 and theDCA terminal 1010 in the camera mount A as one of the main functionsthereof. As described above, two-way communication of communication datais performed via the DCL terminals and via the DCA terminals, andtherefore, the input/output direction of signals is switched by the I/Funit 102.

In this embodiment, a voltage indicated by the communication terminalsthat correspond to the first communication unit is switched between avoltage equal to that of VDD and 3.0 V in accordance with the type ofcamera accessory mounted on the camera body 100. A voltage indicated bythe communication terminals that correspond to the second and thirdcommunication units does not change regardless of the type of cameraaccessory mounted on the camera body 100 and has a constant value (3.0V) at all times.

To the first communication I/F unit 102 a, a power voltage (Vs), whichis a voltage equal to that of VDD or 3.0 V, and a power voltage (3.3 V)having an electric potential identical to a voltage indicated by thecamera controller 101 are applied from the camera power supply unit 103described below. To the second/third communication I/F unit 102 b, apower voltage of 3.0 V and a power voltage (3.3 V) having an electricpotential identical to a voltage indicated by the camera controller 101are applied from the camera power supply unit 103 described below.

Configurations of Camera Power Supply Unit and Power Switching Unit inCamera Body 100

Now, the configuration of the camera power supply unit 103, whichgenerates each power in the camera body 100, is described with referenceto FIG. 3 and FIGS. 8A and 8B. The camera power supply unit 103generates communication control power (VDD) as power to be supplied to amounted camera accessory via the VDD terminal or as power to be suppliedto the first communication I/F unit 102 a via a power switching unit 104described below. The camera power supply unit 103 generates drivingpower (VBAT) as power to be supplied to a mounted camera accessory viathe VBAT terminal. As described above, in this embodiment, the powervoltage of VDD is set to 5.0 V, and the power voltage of VBAT is set to4.5 V.

The camera power supply unit 103 generates power of 3.3 V as power to besupplied to the camera controller 101 and to the I/F unit 102. Thecamera power supply unit 103 generates power of 3.0 V as power to besupplied to the I/F unit 102 via the power switching unit 104 describedbelow.

Now, the power switching unit 104 for switching (the voltage) of powerto be supplied to the first communication I/F unit 102 a is described indetail. The power switching unit 104 is connected to the camera powersupply unit 103. The power switching unit 104 supplies only VDDgenerated by the camera power supply unit 103 or power of 3.0 V to thefirst communication I/F unit 102 a as communication interface power Vs.The power voltage is switched in accordance with an instruction from thecamera controller 101.

In a case where the camera controller 101 uses the TYPE terminal 1003 todetermine that the type of camera accessory mounted on the camera body100 is the first interchangeable lens 200, the camera controller 101controls the power switching unit 104 so that the power Vs becomes powerof 3.0 V. In a case where the camera controller 101 determines that thesecond interchangeable lens 300 is mounted on the camera body 100 withthe adaptor 400 therebetween, the camera controller 101 controls thepower switching unit 104 so that the communication interface power Vshas a voltage equal to that of VDD. During a period in which mounting ofa camera accessory is not detected in the camera body 100 and during aperiod until the type of mounted camera accessory is determined, thecamera controller 101 controls the power switching unit 104 so that thepower Vs is power of 3.0 V. With this configuration, for example, in acase where the first interchangeable lens 200 is mounted directly on thecamera body 100, application of a voltage of 3.0 V or higher to anelectric circuit of the first interchangeable lens 200 having a ratedvoltage of 3.0 V can be prevented.

In a state where mounting of a camera accessory is not detected in thecamera body 100 and during a period until the type of mounted cameraaccessory is determined, the communication interface power Vs need notbe supplied. Similarly, regarding power (3.0 V) to be supplied to thesecond/third communication I/F unit 102 b, the power Vs need not besupplied. With this configuration, application of a predeterminedvoltage to each terminal in a state where power is not supplied from thecamera to the camera accessory can be prevented. As a result, thepossibility of a current of an unintended voltage flowing throughterminals not corresponding to each other when a camera accessory is notmounted can be reduced.

As described above, in the camera body 100, the camera controller 101controls the I/F unit 102 and the power switching unit 104 to enableeach type of communication at an appropriate voltage corresponding tothe type of camera accessory mounted on the camera body 100.

Configuration of Communication Interface Unit in First InterchangeableLens 200

Now, the configuration of a first lens I/F unit 202, which functions asan interface circuit between the communication terminals provided in thefirst interchangeable lens 200 and the first lens controller 201, isdescribed with reference to FIG. 3.

As illustrated in FIG. 3, the first lens I/F unit 202 is provided withinthe first interchangeable lens 200 as a communication interface unit inthe first interchangeable lens 200. The first lens I/F unit 202functions as an interface circuit for the camera body 100 and the firstinterchangeable lens 200 to perform communication via the terminalscorresponding to the first, second, and third communication units.

The first lens I/F unit 202 has a level shifter function for conversionbetween a voltage indicated by the terminals provided in the lens mountB and a voltage indicated by the first lens controller 201 as one of themain functions thereof. The level shifter function is as follows. Forexample, in a case where a voltage level indicated by the first lenscontroller 201 is different from a voltage level indicated by theterminals, the first lens I/F unit 202 performs voltage conversion forthe voltage indicated by the terminals in accordance with the differencebetween the first lens controller 201 and the terminals to adjust thedifference. In a case where the level of a voltage indicated by thefirst lens controller 201 and the level of a voltage indicated by theterminals are equal to each other (3.0 V), as illustrated in FIG. 3, thelevel shifter function described above need not be provided.

The first lens I/F unit 202 has a function of switching the LCLKterminal 2008 between input and open-drain-type output in the lens mountB as one of the main functions thereof. The first lens I/F unit 202further has a function of switching the DLC terminal 2007 betweenopen-drain-type output and CMOS-output-type output in the lens mount Bas one of the main functions thereof.

Control of the LCLK terminal 2008 and the DLC terminal 2007 in a casewhere the first interchangeable lens 200 is mounted on the camera body100 is performed as described in the above description of thecommunication interface in the camera body 100. That is, the first lenscontroller 201 controls the first lens I/F unit 202 to switch the outputtype of the LCLK terminal 2008 and the DLC terminal 2007 in accordancewith the level of a voltage output from the LCLK terminal 2008.

The first lens I/F unit 202 has an input/output direction switchfunction for switching the input/output direction for the DCL terminal2006 and the DCA terminal 2010 in the lens mount B as one of the mainfunctions thereof. As described above, two-way communication ofcommunication data is performed via the DCL terminals and via the DCAterminals, and therefore, the input/output direction of signals isswitched by the first lens I/F unit 202.

Configuration of Lens Power Supply Unit in First Interchangeable Lens200

Now, the configuration of a lens power supply unit 203, which generateseach power in the first interchangeable lens 200, is described withreference to FIG. 3. In a state where the first interchangeable lens 200is mounted on the camera body 100, communication control power (VDD) issupplied to the lens power supply unit 203 of the first interchangeablelens 200 from the camera power supply unit 103 described above via theVDD terminals. In this state, the lens power supply unit 203 generatespower of 3.0 V on the basis of VDD supplied from the camera body 100 asa power voltage to be applied to the first lens controller 201 and tothe first lens I/F unit 202.

In the state where the first interchangeable lens 200 is mounted on thecamera body 100, driving power (VBAT) is supplied to a drive circuitunit 204 of the first interchangeable lens 200 from the camera powersupply unit 103 described above via the VBAT terminals.

In this embodiment, the level of the power voltage of the first lenscontroller 201 and that of the first lens I/F unit 202 are set to thesame level (3.0 V); however, the voltage level indicated by the firstlens controller 201 may be set to 3.3 V. In this case, power of avoltage level of 3.0 V and power of a voltage level of 3.3 V need to besupplied to the first lens I/F unit 202, and therefore, the lens powersupply unit 203 generates power of 3.0 V and power of 3.3 V.

Configuration of Communication Interface Unit in Second InterchangeableLens 300

Now, the configuration of a second lens I/F unit 302, which functions asan interface circuit between the communication terminals provided in thesecond interchangeable lens 300 and the second lens controller 301, isdescribed with reference to FIGS. 8A and 8B.

As illustrated in FIGS. 8A and 8B, the second lens I/F unit 302 isprovided within the second interchangeable lens 300. To the second lensI/F unit 302, the DCL terminal 3006, the DLC terminal 3007, and the LCLKterminal 3008 are connected, and the second lens I/F unit 302 functionsas an interface circuit for first communication performed between thecamera body 100 and the second interchangeable lens 300.

The second lens I/F unit 302 has a level shifter function for convertinga voltage indicated by the terminals provided in the lens mount D and avoltage indicated by the second lens controller 301 as one of the mainfunctions thereof.

The level shifter function is as follows. For example, a case is assumedwhere a voltage level indicated by the terminals is equal to the voltageof VDD and a voltage indicated by the second lens controller 301 is setto 3.3 V. In this case, the second lens I/F unit 302 performs voltageconversion for the voltage indicated by the terminals to adjust thedifference in voltage between the second lens controller 301 and theterminals. In a case where the level of a voltage indicated by thesecond lens controller 301 is equal to the level of a voltage indicatedby the terminals, the level shifter function described above need not beprovided.

The second lens I/F unit 302 has a function of switching the LCLKterminal 3008 between input and open-drain-type output in the lens mountD as one of the main functions thereof. The second lens I/F unit 302further has a function of switching the DLC terminal 3007 betweenopen-drain-type output and CMOS-output-type output in the lens mount Das one of the main functions thereof.

Control of the LCLK terminal 3008 and the DLC terminal 3007 in a casewhere the second interchangeable lens 300 is mounted on the camera body100 with the adaptor 400 therebetween is performed as described in theabove description of the communication interface in the firstinterchangeable lens 200. That is, the second lens controller 301controls the second lens I/F unit 302 to switch the output type of theLCLK terminal 3008 and the DLC terminal 3007 in accordance with thelevel of a voltage output from the LCLK terminal 3008.

Configuration of Lens Power Supply Unit in Second Interchangeable Lens300

Now, the configuration of a lens power supply unit 303, which generateseach power in the second interchangeable lens 300, is described withreference to FIGS. 8A and 8B. In a state where the secondinterchangeable lens 300 is mounted on the camera body 100 with theadaptor 400 therebetween, communication control power (VDD) is suppliedto the lens power supply unit 303 of the second interchangeable lens 300from the camera power supply unit 103 described above via the VDDterminals. In this state, the lens power supply unit 303 generates powerof 3.3 V on the basis of VDD supplied from the camera body 100 as apower voltage to be applied to the second lens controller 301 and to thesecond lens I/F unit 302.

In the state where the second interchangeable lens 300 is mounted on thecamera body 100 with the adaptor 400 therebetween, driving power (VBAT)is supplied to a drive circuit unit 304 of the second interchangeablelens 300 from the camera power supply unit 103 described above via theVBAT terminals.

Internal Configuration of Adaptor 400

Now, the internal configurations and operations of circuits included inthe adaptor 400 are described with reference to FIGS. 8A and 8B. In astate where the adaptor 400 is mounted on the camera body 100,communication control power (VDD) is supplied to the adaptor powersupply unit 403 of the adaptor 400 from the camera power supply unit 103described above via the VDD terminals. In this state, the adaptor powersupply unit 403 generates power to be supplied to the adaptor controller401 including an adaptor CPU and to the adaptor operation input unit 402on the basis of VDD supplied from the camera body 100.

The adaptor operation input unit 402 can be used to input, for example,a setting relating to manual focus and a setting relating to theaperture diameter of the diaphragm through a user operation andincludes, for example, a ring member rotatable in the circumferentialdirection of the adaptor 400 as an operation member that can be manuallyoperated by the user.

The adaptor controller 401 asserts or negates a communication requestfrom the CS terminal 2011 provided in the lens mount B of the adaptor400 in accordance with control by an open interface unit 404 formed ofan N-channel transistor. To the adaptor controller 401, the voltagelevel of the CS terminal 2011 is input to monitor the voltage level ofthe CS terminal 2011.

Operation information input to the adaptor operation input unit 402 isreflected to various settings of the camera body 100 via thirdcommunication between the adaptor controller 401 and the cameracontroller 101 via the terminals that correspond to the thirdcommunication unit. Specifically, when the adaptor controller 401detects operation information input to the adaptor operation input unit402, the adaptor controller 401 controls the open interface unit 404 andtransmits a communication request to the camera controller 101 via theCS terminal 2011 corresponding to the third communication unit. In thiscase, the adaptor controller 401 transmits the detected operationinformation to the camera controller 101 via the DCA terminal 2010corresponding to the third communication unit.

Internal Configuration of Intermediate Accessory 500

Now, the internal configurations and operations of circuits included inthe intermediate accessory 500 are described with reference to FIGS. 10Aand 10B. In a state where the intermediate accessory 500 is mounted onthe camera body 100, communication control power (VDD) is supplied tothe accessory power supply unit 503 of the intermediate accessory 500from the camera power supply unit 103 described above via the VDDterminals. In this state, the accessory power supply unit 503 generatespower to be supplied to the accessory controller 501 including anaccessory CPU and to the accessory operation input unit 502 on the basisof VDD supplied from the camera body 100.

The accessory operation input unit 502 can be used to input, forexample, a setting relating to manual focus and a setting relating tothe aperture diameter of the diaphragm through a user operation andincludes, for example, a ring member rotatable in the circumferentialdirection of the intermediate accessory 500 as an operation member thatcan be manually operated by the user.

The intermediate accessory 500 also includes an open interface unit 504formed of an N-channel transistor as in the adaptor 400 described above.Although a control target differs, the operations of the open interfaceunit 504 are substantially the same as those of the open interface unit404 described above, and therefore, a description thereof will beomitted.

Operation information input to the accessory operation input unit 502 isreflected to various settings of the camera body 100 via thirdcommunication between the accessory controller 501 and the cameracontroller 101 or the first lens controller 201 via the terminals thatcorrespond to the third communication unit. Specifically, when theaccessory controller 501 detects operation information input to theaccessory operation input unit 502, the accessory controller 501controls the open interface unit 504 and transmits a communicationrequest to the camera controller 101 via the CS terminal 2011corresponding to the third communication unit. In this case, theaccessory controller 501 transmits the detected operation information tothe camera controller 101 via the DCA terminal 2010 corresponding to thethird communication unit.

Method for Determining Camera Accessory

Now, a method for the camera body 100 to determine the type of cameraaccessory mounted on the camera body 100 is described with reference toFIG. 11 and Table 1 below. More specifically, a method for the cameracontroller 101 in the camera body 100 to determine the type of cameraaccessory mounted on the camera body 100 on the basis of the level of avoltage indicated by the TYPE terminal 1003 is described.

TABLE 1 First inter- Mounted changeable Adaptor accessory Error 1 lens200 Reserved 400 Error 2 TYPE_IN 0x0000 to 0x0080 to 0x0180 to 0x0280 to0x0380 to terminal 0x007F 0x017F 0x027F 0x037F 0x03FF Communi- No 3.0 VNo VDD No cation communi- communi- (5.0 V) communi- voltage cationcation cation

As described above, Table 1 is a table that indicates a relationshipbetween an input signal of the TYPE terminal and the communicationvoltage in a case where each camera accessory is mounted on the camerabody 100 (including errors and so on). In this embodiment, information(table data) that indicates a relationship between a voltage levelindicated by the TYPE_IN terminal and a mounted accessory as indicatedby Table 1 is stored in a memory (not illustrated) provided in thecamera controller 101. The table data may be recorded to any memory areain a recording unit provided within the camera body 100.

In a case where the first interchangeable lens 200 is mounted on thecamera body 100, the TYPE terminal 1003 is pull-up connected to powerindicating a voltage level of 3.3 V via a resistor R_TYPE_C 126. In thiscase, the TYPE terminal is pull-down connected to the DGND terminal viaa resistor R_TYPE_L 224. Here, in the TYPE terminal 1003, 3.3 V power isdivided into voltages on the basis of the resistance of the resistorR_TYPE_C 126 and that of the resistor R_TYPE_L 224, and the resultingvoltage is applied to the camera controller 101. In this embodiment, theresistance indicated by each of the resistors described above is set inaccordance with the ratio to a resistance indicated by another resistorconnected to a terminal that may be short-circuited by taking intoconsideration a case of an inter-terminal short circuit.

In a case where the adaptor 400 is mounted on the camera body 100, theTYPE terminal is pull-up connected to power indicating a voltage levelof 3.3 V via the resistor R_TYPE_C 126 and pull-down connected to theDGND terminal via a resistor R_TYPE_A 421. In this case, 3.3 V power isdivided into voltages on the basis of the resistance of the resistorR_TYPE_C 126 and that of the resistor R_TYPE_A 421, and the resultingvoltage is applied to the camera controller 101.

Here, the camera controller 101 includes an AD converter for convertingan analog data signal to a digital signal and a TYPE_IN terminal, whichis an input port of the AD converter. To the TYPE_IN terminal, the TYPEterminal 1003 is connected. For description purposes, the resolution ofthe AD converter is assumed to be 10 bits (1024 divisions: 0x0000 to0x03FF). Between the TYPE terminal 1003 and the TYPE_IN terminal, aresistor indicating a predetermined resistance (in this embodiment, 1kΩ) for protecting the TYPE_IN terminal is connected.

For description purposes, a predetermined resistance indicated by eachresistor is assumed as follows. The resistance of the resistor R_TYPE_C126 indicating a pull-up resistance in the camera body 100 is 100 kΩ.The resistance of the resistor R_TYPE_L 224 indicating a pull-downresistance in the first interchangeable lens 200 is 33 kΩ. Theresistance of the resistor R_TYPE_A 421 indicating a pull-downresistance in the adaptor 400 is 300 kg.

The camera controller 101 determines the type of camera accessorymounted on the camera body 100 in accordance with the level of a voltageinput to the TYPE_IN terminal. Specifically, the camera controller 101performs AD conversion of a voltage level input to the TYPE_IN terminal.The camera controller 101 compares a voltage value after AD conversionwith a threshold (reference value) corresponding to each lens type, thethreshold being held in advance in a memory (not illustrated) of thecamera controller 101, to determine the type of camera accessory.

Hereinafter, a specific method for determining each camera accessory isdescribed. FIGS. 11A to 11E are diagrams each illustrating the state ofconnection between the TYPE_IN terminal of the camera body 100 and acamera accessory. FIG. 11A illustrates a case where the firstinterchangeable lens 200 is mounted on the camera body 100. FIG. 11Billustrates a case where the adaptor 400 is mounted on the camera body100. FIG. 11C illustrates a case where the TYPE terminal provided in thecamera body 100 does not properly come into contact with the TYPEterminal provided in a camera accessory due to imperfect contact. FIG.11D illustrates a case where a short circuit occurs between the TYPEterminal and the adjacent VBAT terminal because, for example, aconductive foreign object is adhered between the terminals. FIG. 11Eillustrates a case where a short circuit occurs between the TYPEterminal and the adjacent PGND terminal because, for example, aconductive foreign object is adhered between the terminals.

As illustrated in FIG. 11A, in the case where the first interchangeablelens 200 is mounted on the camera body 100, the level of a voltage inputto the TYPE_IN terminal of the camera controller 101 (after ADconversion) is approximately “0X0103”. In the case illustrated in FIG.11A, the level of the voltage input to the TYPE_IN terminal isdetermined on the basis of the ratio (division ratio) between thepull-up resistance of 100 kΩ and the protective resistance of 1 kΩwithin the camera body 100 and the pull-down resistance of 33 kΩ withinthe first interchangeable lens 200.

The camera controller 101 compares the table data (indicated by Table 1)stored in a memory with the level of the voltage input to the TYPE_INterminal. For example, in the case where the level of the voltage inputto the TYPE_IN terminal (after AD conversion) is “0x0103”, the levelfalls within a voltage level range “0x0080 to 0x017F”, which indicatesthat the first interchangeable lens 200 is mounted, as indicated byTable 1. In this case, the camera controller 101 determines that thefirst interchangeable lens 200 is mounted on the camera body 100.

As illustrated in FIG. 11B, in the case where the adaptor 400 is mountedon the camera body 100, the level of a voltage input to the TYPE_INterminal of the camera controller 101 (after AD conversion) isapproximately “0X0300”. In the case illustrated in FIG. 11B, the levelof the voltage input to the TYPE_IN terminal is determined on the basisof the ratio (division ratio) between the pull-up resistance of 100 kΩand the protective resistance of 1 kΩ within the camera body 100 and thepull-down resistance of 300 kΩ within the adaptor 400.

In this case, the level of the voltage input to the TYPE_IN terminal(after AD conversion) is “0x0300” and falls within a voltage level range“0x0280 to 0x037F”, which indicates that the adaptor 400 is mounted, asindicated by Table 1. Therefore, the camera controller 101 determinesthat the adaptor 400 is mounted on the camera body 100.

As illustrated in FIG. 11C, in the case where the TYPE terminal providedin the camera body 100 imperfectly comes into contact with the TYPEterminal provided in a camera accessory, the level of a voltage input tothe TYPE_IN terminal of the camera controller 101 is approximately“0x03FF”. In this case, the level of the voltage input to the TYPE_INterminal is determined on the basis of only the pull-up resistance of100 kΩ within the camera body 100.

In the above-described case, the level of the voltage input to theTYPE_IN terminal is a voltage that does not correspond to any of thefirst interchangeable lens 200 and the adaptor 400. In this case, thelevel of the voltage input to the TYPE_IN terminal corresponds to error1 indicated by Table 1, and therefore, the camera controller 101 failsto determine a camera accessory mounted on the camera body 100. Thestate illustrated in FIG. 11C corresponds to a case where, for example,the MIF terminal of the camera body 100 and that of the camera accessoryare properly connected to each other but the TYPE terminals do not comeinto contact with each other.

As illustrated in FIG. 11D, in the case where, for example, a conductiveforeign object is adhered between the TYPE terminal and the adjacentVBAT terminal and a short circuit occurs between the TYPE terminal andthe adjacent terminal, the signal line of the VBAT terminal is connectedto the TYPE terminal. At this time, in a case where the type of cameraaccessory mounted on the camera body 100 is determined before power issupplied to the VBAT terminal, the result of determination of the typeof camera accessory may differ depending on the state of the VBAT power.

For example, in a case where the VBAT power is turned off and the signalline of the VBAT power has an electric potential equal to that of thesignal line of the PGND terminal, the signal line of the TYPE terminalhas an electric potential equal to that of the signal line of the PGNDterminal. In this case, the level of a voltage input to the TYPE_INterminal is determined on the basis of the ratio (division ratio)between the pull-up resistance of 100 kΩ and the protective resistanceof 1 kΩ within the camera body 100 and has a value of approximately“0x000A”. In this case, the level of the voltage input to the TYPE_INterminal corresponds to error 1 indicated by Table 1, and therefore, thecamera controller 101 fails to determine a camera accessory mounted onthe camera body 100.

For example, in a case where the VBAT power is turned off and the signalline of the VBAT power is floating, the short circuit between the TYPEterminal and the VBAT terminal has no effect, and the camera controller101 can determine the type of camera accessory as described above.Thereafter, at the time when the VBAT power is supplied to the VBATterminals in a state where the VBAT terminals are connected to eachother, a power voltage equivalent to the VBAT power voltage is appliedto the TYPE terminal. In this case, the VBAT terminals indicate avoltage of a level higher than the power voltage of the TYPE_INterminal, and therefore, a current of an unintended voltage level mayflow into the TYPE_IN terminal via a diode (not illustrated) presentwithin the TYPE_IN terminal.

Accordingly, in the camera body 100 according to this embodiment, theprotective resistor of 1 kΩ is provided in series to the signal line ofthe TYPE terminal. With this configuration, the possibility of a currentof an unintended voltage level flowing into (the power of) the TYPE_INterminal can be reduced, and the occurrence of a failure in each unitconnected to the TYPE_IN terminal can be suppressed. A protective diodemay be connected to the signal line between the protective resistor of 1kΩ and the TYPE_IN terminal.

At the time when the VBAT power is supplied to the VBAT terminal, thecamera controller 101 may detect again the level of a voltage input tothe TYPE_IN terminal to determine the type of camera accessory again. Inthis case, in the state as illustrated in FIG. 11D, a voltage equivalentto the power voltage of the VBAT terminal is applied to the TYPEterminal, and the level of the voltage input to the TYPE_IN terminal isapproximately “0x03FF”. In this case, although the camera controller 101fails to determine the camera accessory mounted on the camera body 100,a current of an unintended voltage level can be prevented from flowinginto the TYPE_IN terminal.

In a case where power is supplied to the VBAT terminal before the typeof camera accessory is determined, AD conversion of the level of avoltage input to the TYPE_IN terminal is performed in a state where apower voltage indicated by the VBAT terminal is applied to the TYPEterminal. In this case, the level of the voltage input to the TYPE_INterminal (after AD conversion) is approximately “0x03FF”. In this case,the level of the voltage input to the TYPE_IN terminal corresponds toerror 1 indicated by Table 1, and therefore, the camera controller 101fails to determine the camera accessory mounted on the camera body 100.

As illustrated in FIG. 11E, in the case where a short circuit occursbetween the TYPE terminal and the adjacent PGND terminal because, forexample, a conductive foreign object is adhered between the TYPEterminal and the adjacent terminal, the TYPE terminal is connected tothe single line of the PGND terminal. In this case, the PGND terminal isa ground terminal, and therefore, a voltage input to the TYPE_INterminal is determined on the basis of the ratio (division ratio)between the pull-up resistance 100 kΩ and the protective resistance 1 kΩwithin the camera body 100 and has a value of approximately “0x000A”.Accordingly, also in this case, the camera controller 101 fails todetermine the camera accessory mounted on the camera body 100.

As described above, in the case where a short circuit occurs between theTYPE terminal and an adjacent terminal, the level of a voltage input tothe TYPE_IN terminal has a value close to a voltage level indicated bythe PGND terminal or a value close to the level of a power voltageindicated by the VBAT terminal. In such a case, the camera controller101 fails to determine the type of camera accessory mounted on thecamera body 100 and is unable to perform operations or give aninstruction for operations suitable to the camera accessory.

Accordingly, in a case where a voltage having a value close to a voltagelevel indicated by the PGND terminal is input to the TYPE_IN terminal ofthe camera controller 101, the camera controller 101 of the camera body100 according to this embodiment performs control so as not to performcommunication with the camera accessory. In this embodiment, in a casewhere the level of a voltage input to the TYPE_IN terminal falls withina range “0x0000 to 0x007F”, the camera controller 101 determines theconnection state of the TYPE terminal to be an abnormal state, namely,an error state, and does not perform communication with the cameraaccessory.

In a case where a voltage having a value equal to a power voltage levelindicated by the VBAT terminal is input to the TYPE_IN terminal, thecamera controller 101 performs control so as not to performcommunication with the camera accessory. In a case where the level of avoltage input to the TYPE_IN terminal falls within a range “0x0380 to0x03FF”, the camera controller 101 according to this embodimentdetermines the connection state of the TYPE terminal to be an abnormalstate, namely, an error state, and does not perform communication withthe camera accessory.

With this configuration, in the camera body 100 according to thisembodiment, a voltage having a level that exceeds the rated voltage canbe prevented from being applied to the camera accessory in a state wherethe type of camera accessory mounted on the camera body 100 iserroneously determined.

Operation when Camera Accessory is Mounted on Camera Body 100

Now, as an operation when a camera accessory is mounted on the camerabody 100, a communication selection process that is a process up to thestart of first communication described above is described with referenceto FIG. 12. FIG. 12 is a flowchart illustrating an operation up to thestart of first communication when a camera accessory is mounted on thecamera body 100. In this embodiment, a program corresponding to theflowchart illustrated in FIG. 12 is stored in a memory (not illustrated)provided in the camera controller 101, and the camera controller 101reads the program from the memory and executes the program. Therefore,it is assumed that an operation in each step described below isperformed by the camera controller 101. The operation need not be anoperation following the predetermined program, and each unit of thecamera body 100 and the camera accessory may give an instruction toperform an operation in a corresponding step. The camera controller 101according to this embodiment functions as a detector that detects thelevel of a voltage indicated by each terminal and a controller thatcontrols communication via each communication terminal.

First, in response to an instruction for turning on the power of thecamera body 100 given by an operation of, for example, a power switch(not illustrated) provided in the camera body 100, a communicationselection process is started. In step S601, the camera controller 101reads the voltage level of a MIF_IN terminal and stores informationregarding the state of the MIF_IN terminal based on the read voltagelevel in a random access memory (RAM) area (not illustrated) in theabove-described memory.

Next, in step S602, on the basis of the information regarding the stateof the MIF_IN terminal stored in the RAM area, if the MIF_IN terminalindicates High, the camera controller 101 determines that no cameraaccessory is mounted on the camera body 100, and the flow returns tostep S601. If the MIF_IN terminal indicates Low, the camera controller101 determines that a camera accessory is mounted on the camera body100.

Next, in step S603, the camera controller 101 reads the level of avoltage input to the TYPE_IN terminal after AD conversion and storesinformation regarding the state of the TYPE_IN terminal based on theread voltage level in the RAM area described above.

Next, in step S604, as the state of the TYPE_IN terminal read from theRAM area, the camera controller 101 determines whether the level of thevoltage input to the TYPE_IN terminal is equal to or larger than“0x0080” and equal to or smaller than “0x017F”. If the camera controller101 determines that the level of the voltage input to the TYPE_INterminal is equal to or larger than “0x0080” and equal to or smallerthan “0x017F”, the flow proceeds to step S605. If the above-describedcondition is not satisfied, the flow proceeds to step S608.

Next, in step S605, the camera controller 101 determines that the cameraaccessory mounted on the camera body 100 is the first interchangeablelens 200 (lens type 1) and controls the power switching unit 104 to setthe communication interface power Vs to 3.0 V.

Next, in step S606, the camera controller 101 starts power supply fromthe camera power supply unit 103 to the VDD terminal.

Next, in step S607, the camera controller 101 sets a communicationvoltage of 3.0 V and starts first communication using the terminalscorresponding to the first communication unit, and the flow proceeds tostep S614.

In step S608, as the state of the TYPE_IN terminal read from the RAMarea, the camera controller 101 determines whether the level of thevoltage input to the TYPE_IN terminal is equal to or larger than“0x0280” and equal to or smaller than “0x037F”. If the camera controller101 determines that the level of the voltage input to the TYPE_INterminal is equal to or larger than “0x0280” and equal to or smallerthan “0x037F”, the flow proceeds to step S609. If the above-describedcondition is not satisfied, the flow proceeds to step S612.

Next, in step S609, the camera controller 101 determines that the cameraaccessory mounted on the camera body 100 is the second interchangeablelens 300 (lens type 2) with the adaptor 400 therebetween and controlsthe power switching unit 104 to set the power Vs to VDD (5.0 V).

Next, in step S610, the camera controller 101 starts power supply fromthe camera power supply unit 103 to the VDD terminal.

Next, in step S611, the camera controller 101 sets a communicationvoltage of 5.0 V and starts first communication using the terminalscorresponding to the first communication unit, and the flow proceeds tostep S614.

In step S612, the camera controller 101 determines that the cameraaccessory mounted on the camera body 100 is a camera accessory notcorresponding to the camera body 100 (Reserved) or determines that apredetermined terminal is in an abnormal (error) state.

Then, in step S613, the camera controller 101 does not startcommunication with the camera accessory and controls each unit of thecamera body 100 to perform a process for warning display regarding, forexample, the error on the display 15, and the flow proceeds to stepS614.

In step S614, the camera controller 101 determines whether aninstruction for turning off the power of the camera body 100 is given byan operation of, for example, the power switch (not illustrated). If thecamera controller 101 determines in step S614 that an instruction forturning off the power is given, the flow proceeds to step S619, thecamera controller 101 turns off the power of the camera body 100, andthe communication selection process ends. If the camera controller 101determines in step S614 that an instruction for turning off the power isnot given, the flow proceeds to step S615.

Next, in step S615, the camera controller 101 reads the level of avoltage of the MIF_IN terminal again and stores information regardingthe state of the MIF_IN terminal based on the read voltage level in theRAM area described above. In the process in step S615, the cameracontroller 101 may update (overwrite) the information regarding thestate of the MIF_IN terminal read in the process in step S601 describedabove or may store the information separately in another memory area.

Next, in step S616, on the basis of the information regarding the stateof the MIF_IN terminal stored in the RAM area, the camera controller 101determines whether the MIF_IN terminal indicates High. If the cameracontroller 101 determines in step S616 that the MIF_IN terminalindicates High, the camera controller 101 determines that the cameraaccessory is dismounted from the camera body 100, and the flow proceedsto step S617. If the camera controller 101 determines in step S616 thatthe MIF_IN terminal does not indicate High (that is, indicates Low), thecamera controller 101 determines that the camera accessory remainsmounted on the camera body 100, and the flow returns to step S614.

In step S617, the camera controller 101 stops communication with thecamera accessory. In step S618, the camera controller 101 stops powersupply from the camera power supply unit 103 to the VDD terminal, andthe flow returns to step S601. Thereafter, the camera controller 101repeatedly performs the processes described above.

Although not illustrated in FIG. 12, at a predetermined timing, thecamera controller 101 determines whether driving power (VBAT) issupplied from the camera body 100 to the camera accessory using the VBATterminal and supplies VBAT in accordance with the result ofdetermination.

Details of First, Second, and Third Communication

Now, various types of communication performed between the camera body100 and a camera accessory mounted on the camera body 100 are described.First, a description of first communication is given. As describedabove, first communication is one type of communication performedbetween the camera body 100 and a camera accessory mounted on the camerabody 100. The first communication unit is a clock synchronouscommunication system or a start-stop synchronous communication systemusing the LCLK terminal, the DCL terminal, and the DLC terminal, whichcorrespond to the first communication unit.

In this embodiment, both the first interchangeable lens 200 and thesecond interchangeable lens 300 support first communication. However,the communication voltage relating to first communication differsbetween the first interchangeable lens 200 and the secondinterchangeable lens 300 as described above.

First communication is used to transmit a drive instruction for, forexample, driving a focus lens, driving a zoom lens, or driving adiaphragm to the camera accessory. In the camera accessory that receivessuch a drive instruction, an operation corresponding to the driveinstruction is performed. First communication is also used to transmitinformation (state information) regarding the state of the cameraaccessory, such as the position of a focus lens, the focal length, andthe aperture diameter (f-number) of the diaphragm, from the cameraaccessory to the camera body 100.

Next, a description of second communication is given. As describedabove, second communication is one type of communication performedbetween the camera body 100 and the first interchangeable lens 200 andis asynchronous communication using the DLC2 terminal, which correspondsto the second communication unit. The second interchangeable lens 300does not include the terminal, such as the DLC2 terminal, correspondingto the second communication unit, and therefore, second communication isnot performed between the camera body 100 and the second interchangeablelens 300.

In second communication, the first interchangeable lens 200 serves as amaster unit (master) and transmits a predetermined amount of opticaldata including the position of a focus lens, the position of a zoomlens, an f-number, and the state of an image stabilizing lens in thefirst interchangeable lens 200 to the camera body 100. In secondcommunication, the camera body 100 serves as a slave unit (slave).Regarding the types of pieces of data transmitted from the firstinterchangeable lens 200 to the camera body 100 and the order in whichthe pieces of data are transmitted, the camera body 100 gives aninstruction to the first interchangeable lens 200 in first communicationdescribed above.

Now, operations in the camera and in the camera accessory in a case ofperforming second communication are described with reference to FIG. 13.FIG. 13 is a flowchart illustrating operations relating to secondcommunication. In this embodiment, a program corresponding to theflowchart illustrated in FIG. 13 is stored in a memory (notillustrated), and the camera controller 101 and the first lenscontroller 201 read the program from the memory and execute the program.Therefore, it is assumed that an operation in each step described belowis performed by the camera controller 101 or the first lens controller201. The operation need not be an operation following the predeterminedprogram, and each unit of the camera body 100 and the firstinterchangeable lens 200 may give an instruction to perform an operationin a corresponding step.

Second communication illustrated in FIG. 13 starts at the timing whencontrol of image capturing of an object is started in the camera body100. First, in step S1301, in the camera body 100, the camera controller101 transmits a request for starting second communication to the firstinterchangeable lens 200 via first communication. The start requesttransmitted in step S1301 includes a register communication command inwhich the types of pieces of data intended to be obtained from the firstinterchangeable lens 200 via second communication and the order in whichthese pieces of data are received are set in advance.

Next, in step S1311, in the first interchangeable lens 200, the firstlens controller 201 receives the start request transmitted from thecamera body 100, and the flow proceeds to step S1312. In step S1312, inthe first interchangeable lens 200, the first lens controller 201generates various pieces of data based on the register communicationcommand included in the start request in the specified order.

Next, in step S1313, the first lens controller 201 transmits the piecesof data generated in the first interchangeable lens 200 to the camerabody 100 via second communication. That is, in step S1313, the firstlens controller 201 transmits the pieces of data generated in the firstinterchangeable lens 200 to the camera body 100 using the DLC2 terminal2009 of the first interchangeable lens 200 and the DLC2 terminal 1009 ofthe camera body 100.

Next, in the camera body 100, in the process in step S1302, the cameracontroller 101 sequentially receives the pieces of data transmitted fromthe first interchangeable lens 200 via second communication and endssecond communication when reception of the specified pieces of data iscompleted. In this embodiment, each time control of image capturing ofan object is started, the flow illustrated in FIG. 13 is performed.

As described above, in a case of performing second communication, astart request is transmitted via first communication; however,communication using an independent communication system different fromthe communication system of first communication described above can beperformed using the terminal corresponding to the second communicationunit different from the terminals corresponding to the firstcommunication unit. With this configuration, communication of variouspieces of data (for example, optical data) can be performed between thecamera body 100 and the first interchangeable lens 200 as secondcommunication without interfering with communication (for example, acontrol request to an actuator) performed in first communication. Asdescribed above, a request for starting second communication istransmitted from the camera body 100 to the first interchangeable lens200 via first communication, and therefore, first communication needs tobe established before second communication is performed.

Now, a description of third communication is given. As described above,third communication is one type of communication performed between thecamera body 100 and the first interchangeable lens 200, between thecamera body 100 and the adaptor 400, and between the camera body 100 andthe intermediate accessory 500. Third communication is asynchronouscommunication using the DCA terminal and the CS terminal, whichcorrespond to the third communication unit. As described above, thesecond interchangeable lens 300 does not include the terminals thatcorrespond to the third communication unit, and therefore, thirdcommunication is not performed between the camera body 100 and thesecond interchangeable lens 300.

In third communication, the camera body 100 serves as a master unit(master) in communication, and the first interchangeable lens 200, theadaptor 400, or the intermediate accessory 500 that is directly orindirectly mounted on the camera body 100 serves as a slave unit (slave)in communication.

In the examples described above, the case has been described where oneadaptor 400 or one intermediate accessory 500 is interposed between thecamera body 100 and a predetermined interchangeable lens, as illustratedin FIG. 6 or FIG. 9; however, the examples are not restrictive. Forexample, one or more adaptors 400 and/or one or more intermediateaccessories 500, namely, two or more camera accessories in total, may beinterposed between the camera body 100 and a predeterminedinterchangeable lens. Therefore, in third communication, a plurality ofslaves may be connected in series to one master involved incommunication. Accordingly, third communication allows switching betweena broadcast communication mode in which a signal is transmitted from thecamera body 100 to a plurality of camera accessories (slaves)simultaneously and a P2P (peer-to-peer) mode in which a specific cameraaccessory is specified and communication is performed for the specifiedcamera accessory.

In the broadcast communication mode and in the P2P mode in thirdcommunication, the DCA terminal functions as a communication dataterminal that allows two-way communication. The CS terminal functionsdifferently in the broadcast communication mode and in the P2P mode.Regarding the details, broadcast communication is first described withreference to FIG. 14. FIG. 14 is a timing chart illustrating broadcastcommunication in third communication. FIG. 14 illustrates a case wherethe first interchangeable lens 200 is mounted on the camera body 100with the intermediate accessory 500 therebetween.

In FIG. 14, in broadcast communication in third communication,communication signals via the CS terminals are illustrated as “CS(camera)”, “CS (lens)”, and “CS (accessory)”. Communication signals viathe DCA terminals are illustrated as “DCA (camera)”, “DCA (lens)”, and“DCA (accessory)”. In FIG. 14, “CS” and “DCA” represent signal waveformsrespectively indicated by the CS terminals and the DCA terminals in thecamera body 100, in the intermediate accessory 500, and in the firstinterchangeable lens 200 at predetermined communication control timings.Hereinafter, a case is described where, in response to broadcastcommunication from the camera controller 101 to the first lenscontroller 201 and to the accessory controller 501, broadcastcommunication is performed from the accessory controller 501 to thecamera controller 101 and to the first lens controller 201.

In a description given below, a signal line connected to the CS terminalis referred to as a signal line CS, and a signal line connected to theDCA terminal is referred to as a signal line DCA. At the timing <1>illustrated in FIG. 14, the camera controller 101 starts Low output tothe signal line CS. This operation is an operation for sending anotification of the start of broadcast communication from the cameracontroller 101, which is a communication master, to the first lenscontroller 201 and to the accessory controller 501, which arecommunication slaves.

Next, at the timing <2> illustrated in FIG. 14, the camera controller101 outputs transmission target data to the signal line DCA. At thetiming <3> illustrated in FIG. 14, the first lens controller 201 and theaccessory controller 501 detect the start bit ST input to the signalline DCA and start Low output to the signal line CS. The cameracontroller 101 started Low output to the signal line CS at the timing<1>, and therefore, the signal level of the signal line CS in the cameradoes not change at the timing <3>.

Next, when output up to the stop bit SP in the transmission data iscompleted at the timing <4> illustrated in FIG. 14, the cameracontroller 101 stops Low output to the signal line CS at the timing <5>.When the first lens controller 201 and the accessory controller 501 havereceived the data up to the stop bit SP, the first lens controller 201and the accessory controller 501 analyze the received data and performinternal processing for the received data. When the first lenscontroller 201 and the accessory controller 501 have completed theinternal processing and are ready to receive next data, the first lenscontroller 201 and the accessory controller 501 respectively stop Lowoutput to the signal line CS at the timings <7> and <6> illustrated inFIG. 14.

The time taken to perform an analysis of the received data and internalprocessing of the received data differs depending on the processingcapacity of the CPU provided in each controller. Therefore, forcontinuous communication, each controller needs to know the timing atwhich the other controller completes internal processing of the receiveddata.

In this embodiment, the CS terminal performs open-drain-type output asdescribed above. Therefore, the signal level of the signal line CSbecomes High output when all of the camera controller 101, the firstlens controller 201, and the accessory controller 501 stop Low output tothe signal line CS. That is, each controller (CPU) involved in broadcastcommunication checks to see that the signal level of the signal line CSbecomes High output and determines that the other controllers (CPUs) areready to perform next communication. With this configuration, the camerabody 100 and a predetermined camera accessory according to thisembodiment can continuously perform appropriate communication.

Next, at the timing <8> illustrated in FIG. 14, the accessory controller501 checks to see that High output of the signal line CS is stopped.Then, the accessory controller 501 starts Low output to the signal lineCS to send a notification of the start of broadcast communication to thecamera controller 101 and to the first lens controller 201.

Next, at the timing <9> illustrated in FIG. 14, the accessory controller501 outputs transmission target data to the signal line DCA.

The camera controller 101 and the first lens controller 201 detect thestart bit ST input from the signal line DCA and start Low output to thesignal line CS at the timing <10> illustrated in FIG. 14. The accessorycontroller 501 started Low output to the signal line CS at the timing<8>, and therefore, the signal level of the signal line CS in theaccessory does not change at the timing <10>.

Next, at the timing <11> illustrated in FIG. 14, the accessorycontroller 501 completes output up to the stop bit SP, and thereafter,the accessory controller 501 stops Low output to the signal line CS atthe timing <12>. The camera controller 101 and the first lens controller201 receive the data up to the stop bit SP input from the signal lineDCA. Thereafter, the camera controller 101 and the first lens controller201 analyze the received data and perform internal processing associatedwith the received data, and stop Low output to the signal line CS at thetimings <14> and <13> respectively at which the camera controller 101and the first lens controller 201 are ready to receive next data.

As described above, in the broadcast communication mode of thirdcommunication according to this embodiment, the signal line CS functionsas a signal line for transmitting a signal indicating that broadcastcommunication starts and is in progress (ongoing).

Now, the functions of the CS terminal in the P2P mode in thirdcommunication are described with reference to FIG. 15. FIG. 15 is atiming chart illustrating P2P communication in third communication. FIG.15 illustrates a case where the first interchangeable lens 200 ismounted on the camera body 100 with the intermediate accessory 500therebetween. The signal lines and the signal waveforms illustrated inFIG. 15 are substantially the same as those in the broadcastcommunication mode described with reference to FIG. 14, and therefore,descriptions thereof will be omitted.

Hereinafter, a case is described where the camera controller 101transmits one-byte data to the first lens controller 201, and the firstlens controller 201 transmits two-byte data to the camera controller 101in response to the one-byte data.

In a description given below, a signal line connected to the CS terminalis referred to as a signal line CS, and a signal line connected to theDCA terminal is referred to as a signal line DCA. At the timing <15>illustrated in FIG. 15, the camera controller 101 sends to the firstlens controller 201 an instruction for making specific data betransmitted via the signal line DCA.

Next, at the timing <16> illustrated in FIG. 15, output up to the stopbit SP is completed on the signal line DCA of the camera, andthereafter, the camera controller 101 starts Low output to the signalline CS at the timing <17>. Then, the camera controller 101 makes itselfready for receiving data while outputting Low to the signal line CS andstops Low output to the signal line CS at the timing <18> at which thecamera controller 101 is ready for reception.

After the first lens controller 201 has detected the Low signal on thesignal line CS output by the camera controller 101, the first lenscontroller 201 analyzes the instruction received from the cameracontroller 101 and performs internal processing relating to theinstruction. Subsequently, the first lens controller 201 checks to seethat Low output of the signal line CS in the camera was stopped, andthereafter, the first lens controller 201 transmits data correspondingto the instruction received from the camera controller 101, by using thesignal line DCA at the timing <19> illustrated in FIG. 15.

Next, at the timing <20> illustrated in FIG. 15, the first lenscontroller 201 completes output up to the stop bit SP of the secondbyte, and thereafter, the first lens controller 201 starts Low output tothe signal line CS of the lens at the timing <21>. Subsequently, thefirst lens controller 201 is ready for receiving next data, andthereafter, the first lens controller 201 stops Low output to the signalline CS at the timing <22> illustrated in FIG. 15. In the description ofFIG. 15, the accessory controller 501, which is not selected as acommunication partner in P2P communication, is not involved in variousoperations on the signal line CS and the signal line DCA.

As described above, in the P2P mode of third communication according tothis embodiment, the signal line CS functions as a signal line forsending a notification of the end of transmission of data on thetransmission side and for sending a standby request relating to datatransmission.

As described above, in third communication according to this embodiment,the CS terminal functions differently in the broadcast communicationmode and in the P2P mode. With this configuration, the signal line CSand the signal line DCA respectively relating to the CS terminal and theDCA terminal, namely, only two signal lines in total, are used to enablecommunication in both the broadcast communication mode and in the P2Pmode.

Transmission and reception of various types of data using thirdcommunication are performed using the DCA terminal in which the outputtype is the CMOS output type. With this configuration, even if theoutput type of the CS terminal is the open drain type, high-speedcommunication is enabled.

Order in which Terminals are Arranged

On the basis of the circuit configurations and the operations of thecamera body 100 and each camera accessory described above, thearrangement of the terminals disposed in the camera mount A and in thelens mount B according to this embodiment is described in detail below.

First, the arrangement of the MIF terminals is described. Here, a caseis assumed where the MIF terminal 1005 in the camera mount is disposedat a position so that the MIF terminal 1005 slides on terminals (contactfaces) other than the MIF terminal 2005 disposed in the lens mount B, orconnection of the MIF terminals is completed prior to connection of theDGND terminals and the PGND terminals. In this case, in a state wherethe lens mount B is not completely mounted on the camera mount A, poweris not supplied from the camera body 100 to the camera accessory.Therefore, when the terminals provided in the lens mount B slide on theterminals in the camera mount A, and the MIF terminal 1005 comes intocontact with a terminal other than the MIF terminal 2005, a voltagelevel indicated by the MIF terminal 1005 may instantaneously become Low.

In this case, although the terminals of one of the mounts and thecorresponding terminals of the other mount are not completely connectedto each other, the camera body 100 erroneously detects mounting of thecamera accessory. Therefore, power supply may be started in a statewhere the camera accessory is not completely mounted on the camera body100, power supply and ground connection might not be electricallystable, and a malfunction or a failure may occur in the camera body 100and in the camera accessory. This issue may similarly arise in a casewhere the MIF terminals are connected to each other prior to connectionof the ground terminals.

For the issues described above, in this embodiment, in the camera mountA and in the lens mount B, the MIF terminals 1005 and 2005 are disposedon the far side in the lens mount direction on the camera mount lowerstage and on the lens mount upper stage respectively. That is, in thisembodiment, the terminals are disposed at positions so that the MIFterminal 1005 of the camera mount A does not slide on any terminalsother than the MIF terminal 2005 of the lens mount B when the lens mountis mounted on or dismounted from the camera mount. With this structure,erroneous detection of mounting of a camera accessory by the camera body100 can be prevented. Further, with this structure, power is suppliedfrom the camera body 100 to the camera accessory in a state where thecorresponding power-supply-system terminals are connected to each otherand the corresponding ground terminals are connected to each other withcertainty. Therefore, in the camera body 100 and each camera accessoryaccording to this embodiment, the possibility of a malfunction or afailure in the camera body 100 and in the camera accessory can bereduced.

Next, the arrangement of the DLC terminal, the DCL terminal, and theLCLK terminal, which correspond to the first communication unit, isdescribed. As described above, drive control information and stateinformation are obtained using first communication between the camerabody 100 and the first interchangeable lens 200 and between the camerabody 100 and the second interchangeable lens 300, for example. In otherwords, main data used in an operation of image capturing of an objectusing the camera body 100 is transmitted and received via firstcommunication. Even if terminals slide on other terminals, and theterminals corresponding to the second and third communication units wearout, resulting in unstable electrical connections between the terminalscorresponding to the second and third communication units, main drivecontrol for the camera accessory involved in the image capturingoperation can be performed as long as first communication is properlyperformed. Therefore, the terminals corresponding to the firstcommunication unit are more important terminals for performing an imagecapturing operation than the terminals corresponding to the second andthird communication units.

Accordingly, in the camera mount A according to this embodiment, theterminals corresponding to the first communication unit are disposed atpositions so that the number of times the terminals slide on otherterminals (the number of times the terminals come into contact withother terminals) is smaller than the number of times the terminalscorresponding to the second and third communication units slide on otherterminals. Specifically, in the camera mount A according to thisembodiment, the DLC terminal, the DCL terminal, and the LCLK terminal,which correspond to the first communication unit, are disposed furtherin the lens mount direction than the DLC2 terminal, the CS terminal, andthe DCA terminal. The DLC terminal, the DCL terminal, and the LCLKterminal, in the camera mount A, which correspond to the firstcommunication unit, are disposed at positions so that the number oftimes the terminals slide on other terminals (the number times theterminals come into contact with other terminals) is smallest next tothe MIF terminal. Therefore, in the lens mount B, the terminals of thelens mount B are disposed according to the disposition of the terminalsof the camera mount A.

With this structure, durability to sliding (contact) of terminalscorresponding to the number of times a camera accessory is mounted onand dismounted from the camera body 100 can be increased for the groupof terminals corresponding to the first communication unit to a largerdegree than for the terminals corresponding to the second and thirdcommunication units. Therefore, in the camera body 100 and in the cameraaccessories according to this embodiment, the possibility of acommunication failure due to wearing out of the contact pins and contactfaces corresponding to the DCL terminals, the DLC terminals, and theLCLK terminals, which correspond to the first communication unit, can bereduced, and communication reliability of the camera body 100 and thecamera accessories can be increased.

Next, the arrangement of the DGND terminal and the CS terminal isdescribed with reference to FIGS. 16A and 16B. FIGS. 16A and 16B arediagrams illustrating the internal configuration of the CS terminal, theDCA terminal, and the DGND terminal in the camera mount A and in thelens mount B. FIG. 16A illustrates an example where the DCA terminal isdisposed adjacent to the DGND terminal, which is different from theorder in which the terminals are disposed as described in thisembodiment. FIG. 16B illustrates the order in which the terminals aredisposed according to this embodiment.

As described above, the DCA terminal is a CMOS-output-type terminal.Therefore, when an inter-terminal short circuit occurs between the DCAterminal and the DGND terminal, as illustrated in FIG. 16A, a relativelylarge current flows in the direction indicated by the arrows in FIG.16A. Specifically, when a voltage level indicated by the DCA terminal isset to High output in a state where, for example, a conductive foreignobject is adhered between the DCA terminal and the DGND terminal, ashort circuit occurs between the DCA terminal, which is aCMOS-output-type terminal, and the DGND terminal. In this case, anunintended large current may flow into the DGND terminal of the cameraalong the path indicated by the arrows illustrated in FIG. 16A. Then, afailure may occur in an electric circuit in the camera body 100.

On the other hand, in this embodiment, the DGND terminal is adjacent tothe CS terminal, as illustrated in FIG. 16B. As described above, the CSterminal is a terminal that performs open-type output. Therefore, evenin a case where, for example, a conductive foreign object is adheredbetween the DGND terminal and the CS terminal, and a short circuitoccurs between the DGND terminal and the CS terminal, only a smallcurrent flows into the DGND terminal along the path indicated by thearrows illustrated in FIG. 16B. Specifically, the CS terminal is aterminal that indicates open-type output, and therefore, even in a casewhere a short circuit occurs between the DGND terminal and the CSterminal, only a small current of a low voltage level flows into theDGND terminal of the camera from the power supply of the camera via apull-up resistor. Therefore, in the camera body 100 and the cameraaccessories according to this embodiment, which employ theabove-described configuration, a failure that may occur in an electriccircuit in the camera body 100 due to a large current flowing into theground via the DGND terminal of the camera can be prevented.

Now, the arrangement of the DLC2 terminal and the LCLK terminal isdescribed with reference to FIGS. 17A to 17D. FIGS. 17A to 17D arediagrams each illustrating an effect, produced in an electric circuit,that differs depending on a terminal that is disposed adjacent to theLCLK terminal. FIG. 17A illustrates a case where the CS terminal isdisposed adjacent to the LCLK terminal. FIG. 17B illustrates a casewhere the DCA terminal is disposed adjacent to the LCLK terminal. FIG.17C illustrates a case where the DLC2 terminal is disposed adjacent tothe LCLK terminal and a foreign object is present between the terminals.FIG. 17D illustrates a case where the DLC2 terminal is disposed adjacentto the LCLK terminal and a bent terminal comes into contact with anadjacent terminal. FIGS. 17A to 17D illustrate a case where the secondinterchangeable lens 300 is mounted on the camera body 100 with theadaptor 400 therebetween.

As illustrated in FIG. 17A, the example case is assumed where the CSterminal is disposed adjacent to the LCLK terminal in the camera body100 and in the adaptor 400. FIG. 17A illustrates the case where aconductive foreign object 90 is present between the LCLK terminal andthe CS terminal of the adaptor 400, and the terminals are electricallycontinuous, resulting in a short circuit between the terminals.

The case is assumed where the second interchangeable lens 300 is mountedon the camera body 100 with the adaptor 400 therebetween. In this case,the signal lines of the LCLK terminals are pull-up connected to VDD (5.0V) via the resistor R_LCLK_C 120 in the camera body 100 and via aresistor R_LCLK_L 320 in the second interchangeable lens 300respectively, as illustrated. The CS terminals are pull-up connected toa voltage level of 3.0 V via a resistance (resistor) provided within thecamera body 100 and via a resistance (resistor) provided within theadaptor 400 respectively.

In this case, when a short circuit occurs between the LCLK terminal andthe CS terminal, a voltage of 3.0 V or more is applied to the signallines of the CS terminals from the signal lines of the LCLK terminalsvia the resistor R_LCLK_C 120 and via the resistor R_LCLK_L 320respectively. Both the second/third communication I/F unit 102 b and theadaptor controller 401 usually operate with power of a power voltage of3.0 V. However, if a short circuit occurs between the terminals asdescribed above, a voltage equal to or higher than an upper-limitvoltage is applied to elements, such as the second/third communicationI/F unit 102 b and the adaptor controller 401. As a result, a failuremay occur in an electric circuit in the adaptor 400 and in the camerabody 100.

The upper-limit voltage is a rated voltage and is a voltage at which afailure does not occur in an electric circuit connected to eachterminal. Alternatively, the upper-limit voltage is an operating voltageand is a voltage at which an electric circuit connected to each terminalcan normally operate.

As illustrated in FIG. 17B, the example case is assumed where the DCAterminal is disposed adjacent to the LCLK terminal in the camera body100 and in the adaptor 400. FIG. 17B illustrates the case where theconductive foreign object 90 is present between the LCLK terminal andthe DCA terminal of the adaptor 400, and the terminals are electricallycontinuous, resulting in a short circuit between the terminals.

The case is assumed where the second interchangeable lens 300 is mountedon the camera body 100 with the adaptor 400 therebetween. In this case,the signal lines of the LCLK terminals are pull-up connected to VDD (5.0V) via the resistor R_LCLK_C 120 in the camera body 100 and via theresistor R_LCLK_L 320 in the second interchangeable lens 300respectively, as illustrated. The DCA terminals are pull-up connected toa voltage level of 3.0 V via a resistance (resistor) provided within thecamera body 100 and via a resistance (resistor) provided within theadaptor 400 respectively.

In this case, when a short circuit occurs between the LCLK terminal andthe DCA terminal, a voltage of 3.0 V or more is applied to the signallines of the DCA terminals from the signal lines of the LCLK terminalsvia the resistor R_LCLK_C 120 and via the resistor R_LCLK_L 320respectively. Both the second/third communication I/F unit 102 b and theadaptor controller 401 usually operate with power of a power voltage of3.0 V. However, if a short circuit occurs between the terminals asdescribed above, a voltage equal to or higher than the upper-limitvoltage is applied to elements, such as the second/third communicationI/F unit 102 b and the adaptor controller 401. As a result, a failuremay occur in an electric circuit in the adaptor 400 and in the camerabody 100.

For the above-described reasons, it is not desirable to set the CSterminal or the DCA terminal as a terminal, corresponding to the secondand third communication units, that is adjacent to the LCLK terminal,which corresponds to the first communication unit, on the near side inthe lens mount direction.

Hereinafter, the case where the DLC2 terminal is disposed adjacent tothe LCLK terminal as the configuration according to this embodiment isdescribed. As illustrated in FIG. 17C, the case is assumed where theLCLK terminal and the DLC2 terminal are arranged adjacent to each other,and a short circuit occurs between the terminals due to the presence ofthe conductive foreign object 90. In this case, the secondinterchangeable lens 300 does not include the terminal (DLC2 terminal)that corresponds to the second communication unit as described above.Therefore, even if the second interchangeable lens 300 is mounted on thecamera body 100 with the adaptor 400 therebetween, second communicationis not performed. That is, in the case where the second interchangeablelens 300 is mounted on the camera body 100 with the adaptor 400therebetween, the DLC2 terminal, which corresponds to the secondcommunication unit, is not used between the camera body 100 and thesecond interchangeable lens 300.

Therefore, in the case where the second interchangeable lens 300 ismounted on the camera body 100 with the adaptor 400 therebetween, evenif a short circuit occurs between the LCLK terminal and the DLC2terminal, a failure does not occur in an electric circuit, such as theadaptor controller 401, in the adaptor 400. Even if a short circuitoccurs between the LCLK terminal and the DLC2 terminal, the resistanceis divided on the basis of the resistors provided in the secondinterchangeable lens 300, the adaptor 400, and the camera body 100, anda voltage to be applied to each of the terminals can be suppressed tothe upper-limit voltage of the terminal or lower, which will bedescribed in detail below. That is, it is desirable to arrange theterminal (DLC2 terminal) that corresponds to the second communicationunit adjacent to the terminal that corresponds to the firstcommunication unit. With this configuration, in the camera body 100 andin the adaptor 400 according to this embodiment, a failure in anelectric circuit included in the adaptor 400 and a failure in anelectric circuit included in the camera body 100 can be prevented.

In a case where the first interchangeable lens 200 is mounted on thecamera body 100, the communication voltage of the first communicationunit and that of the second communication unit are the same (3.0 V). Inthis case, even in a case where a short circuit occurs between the LCLKterminal and the DLC2 terminal, a voltage equal to or higher than theupper-limit voltage is not applied to an element, such as the I/F unit102, of the camera body 100 as described above.

In the case where the first interchangeable lens 200 is mounted on thecamera body 100, second communication and third communication may besimultaneously used independently of each other. In this case, even if ashort circuit occurs between the DLC2 terminal corresponding to thesecond communication unit and the DCA terminal corresponding to thethird communication unit, the communication voltage of the secondcommunication unit and that of the third communication unit are the same(3.0 V), and therefore, a voltage equal to or higher than the operatingvoltage is not applied to the second/third communication I/F unit 102 b.

As described above, it is desirable to dispose the terminal (DLC2terminal) corresponding to the second communication unit next to theterminal corresponding to the first communication unit and to disposethe terminal (CS terminal or DCA terminal) corresponding to the thirdcommunication unit next to the terminal corresponding to the secondcommunication unit on the side opposite the terminal corresponding tothe first communication unit. That is, it is desirable to dispose theterminal corresponding to the third communication unit adjacent to theDLC2 terminal corresponding to the second communication unit on one sideof the DLC2 terminal opposite the LCLK terminal corresponding to thefirst communication unit, the LCLK terminal being disposed adjacent tothe DLC2 terminal on the other side, so that the DLC2 terminal isdisposed between the LCLK terminal and the terminal corresponding to thethird communication unit. With this configuration, even in a case wherean interchangeable lens is mounted directly or indirectly on the camerabody 100, a failure that may occur in an electric circuit in the camerabody 100 and in an electric circuit in the adaptor 400 can be prevented.

Now, a voltage applied to each interface unit within the camera body 100is described in detail. Here, a case is assumed where the secondinterchangeable lens 300 is mounted on the camera body 100 with theadaptor 400 therebetween. In this case, the signal lines of the LCLKterminals are pull-up connected to VDD (5.0 V) via the resistor R_LCLK_C120 in the camera body 100 and via the resistor R_LCLK_L 320 in thesecond interchangeable lens 300 respectively. The DLC2 terminals arepull-down connected to the signal lines of the DGND terminals via theresistor R_DLC2_C 122 provided within the camera body 100 and via theresistor R_DLC2_A 422 provided within the adaptor 400 respectively.

Here, the combined resistance of R_LCLK_C 120 and R_LCLK_L 320 isdenoted as R_LCLK, and the combined resistance of R_DLC2_C 122 andR_DLC2_A 422 is denoted as R_DLC2. A voltage that is applied to thesignal line of the LCLK terminal and that of the DLC2 terminal in a caseof a short circuit between the terminals as described above is denotedas V_ST1. Then, the combined resistance R_LCLK, the combined resistanceR_DLC2, and the applied voltage V_ST1 are respectively calculated byusing expressions (1), (2), and (3) below.R_LCLK=1/((1/R_LCLK_C120)+(1/R_LCLK_L320))  (1)R_DLC2=1/((1/R_DLC2_C122)+(1/R_DLC2_A422))  (2)V_ST1=5.0×(R_DLC2/(R_LCLK+R_DLC2))  (3)

For example, in a case where R_LCLK is set to 10 kΩ, and R_DLC2 is setto 100 kΩ, expressions (1), (2), and (3) are used to obtain the appliedvoltage V_ST1≈4.5 V. As a result, a voltage that exceeds the upper-limitvoltage (3.0 V) of the second/third communication I/F unit 102 b isapplied.

Accordingly, in this embodiment, for example, R_LCLK is set to 10 kΩ andR_DLC2 is set to 10 kΩ to adjust the applied voltage so that the appliedvoltage, which is V_ST1=2.5 V, is equal to or lower than the upper-limitvoltage (3.0 V) of the second/third communication I/F unit 102 b. To setthe applied voltage to a value equal to or lower than the upper-limitvoltage of the second/third communication I/F unit 102 b, expression (4)below needs to be satisfied.(R_DLC2/(R_LCLK+R_DLC2))≤(3.0/VDD)  (4)

When the resistance of R_LCLK_C 120, that of R_LCLK_L 320, that ofR_DLC2_C 122, and that of R_DLC2_A 422 are set so as to satisfyexpression (4) above, the second/third communication I/F unit 102 b canbe protected from overvoltage.

In this embodiment, the camera controller 101 detects the LCLK terminalswitching from the Low level to the High level immediately after apredetermined interchangeable lens is mounted, as described above. In acase where the interchangeable lens is the second interchangeable lens300, the camera controller 101 performs open-drain-output-typecommunication with the second interchangeable lens 300 to determine, viathe communication, whether the second interchangeable lens 300 supportsCMOS-output-type communication. If the second interchangeable lens 300is determined to support CMOS-output-type communication, the cameracontroller 101 switches the output system of the LCLK terminal and theDCL terminal to the CMOS output type. In the case where the cameracontroller 101 switches the output type of the LCLK terminal and the DCLterminal to the CMOS output type, a voltage indicated by the LCLKterminal 1008 is equal to a power voltage (5.0 V) output from the firstcommunication I/F unit 102 a without passing through R_LCLK_C 120.

It is assumed that the Low-level input threshold (VIL_LCLK) for theinput terminal of the first communication I/F unit 102 a for the LCLKsignal is 0.5 V and that R_LCLK=10 kΩ, R_DLC2_A 422=470Ω, and R_DLC2_C122=10 kΩ are satisfied. In this case, the applied voltage V_ST1≈0.2 Vobtained on the basis of expressions (2) and (3) is smaller than theLow-level input threshold for the first communication I/F unit 102 a.Therefore, the camera controller 101 determines that communication withthe interchangeable lens is not possible, and performs control so as notto start communication with the lens.

With this configuration, in the camera body 100, the output type of theLCLK terminal does not switch to the CMOS output type. Accordingly, avoltage equal to or higher than the upper-limit voltage can be preventedfrom being applied to an element, such as the second/third communicationI/F unit 102 b. To prevent the output type of the LCLK terminal fromswitching to the CMOS output type in the camera body 100, expression (5)below needs to be satisfied.(R_DLC2/(R_LCLK+R_DLC2))≤VIL_LCLK  (5)

When the resistance of R_LCLK_C 120, that of R_LCLK_L 320, that ofR_DLC2_C 122, and that of R_DLC2_A 422 are set so as to satisfyexpression (5) above, the second/third communication I/F unit 102 b canbe protected from overvoltage.

However, even in a case where expression (5) above is satisfied, if theresistance of R_DLC2_C 122 is small, the terminal current of the firstlens I/F unit 202 needs to be set to have a large value in a case ofsecond communication using the DLC2 terminal. This corresponds to a casewhere, for example, R_DLC2_A 422 is set to 10 kΩ and R_DLC2_C 122 is setto 470Ω. In this embodiment, the resistances are set so that R_DLC2_A422=470Ω is smaller than R_DLC2_C 122=10 kΩ by taking into considerationsecond communication.

As illustrated in FIG. 17D, the case is assumed where the LCLK terminaland the DLC2 terminal are arranged adjacent to each other and where thecontact pin of the DLC2 terminal 1009 provided in the camera body 100 isbent and a short circuit occurs between the DLC2 terminal 1009 and theadjacent LCLK terminal. Terminal processing for the LCLK terminal andthe DLC2 terminal is performed as described above, and therefore, adescription thereof will be omitted.

In the case as illustrated in FIG. 17D, a voltage applied to the LCLKterminal and to the DLC2 terminal 1009 of the camera body 100 is denotedas V_ST2. In this case, the applied voltage V_ST2 is calculated by usingexpression (6).V_ST2=5.0×R_DLC2_C122/(R_LCLK+R_DLC2_C122)  (6)

It is assumed that, for example, R_LCLK is equal to 10 kΩ and R_DLC2_C122 is equal to 100 kΩ. Then, expressions (1) and (6) are used to obtainV_ST2=4.5 V. As a result, a voltage that exceeds the upper-limit voltage(3.0 V) of the second/third communication I/F unit 102 b is applied. Inthis case, a failure may occur in an electric circuit, such as thesecond/third communication I/F unit 102 b, in the camera body 100 asdescribed above.

Accordingly, in this embodiment, for example, R_LCLK is set to 10 kΩ andR_DLC2_C 122 is set to 10 kΩ to adjust the applied voltage so that theapplied voltage, which is V_ST2=2.5 V, is equal to or lower than theupper-limit voltage (3.0 V) of the second/third communication I/F unit102 b. To make the applied voltage be equal to or lower than theupper-limit voltage of the second/third communication I/F unit 102 b,expression (7) below needs to be satisfied. The High-level inputthreshold for the input terminal of the second/third communication I/Funit 102 b for the DLC2 signal is denoted as VIH_DLC2.VIH_DLC2≤R_DLC2/(R_LCLK+R_DLC2)≤(3.0/VDD)  (7)

When the resistance of R_LCLK_C 120, that of R_LCLK_L 320, and that ofR_DLC2_C 122 are set so as to satisfy expression (7) above, thesecond/third communication I/F unit 102 b can be protected fromovervoltage.

Here, in a case where the second interchangeable lens 300 is mounted onthe camera body 100 with the adaptor 400 therebetween, the DLC2 terminalis pull-down connected to the DGND signal line via the resistance(resistor) R_DLC2_A 422 provided within the adaptor 400. In this case,it is anticipated that a Low-level voltage is input to the DLC2 inputterminal (DLC2_IN) provided in the camera controller 101.

It is assumed that the High-level input threshold VIH_DLC2 for the inputterminal for the DLC2 signal is 2.3 V, R_LCLK is 10 kΩ, and R_DLC2_C 122is 10 kΩ. In this case, the applied voltage V_ST2 calculated usingexpression (6) is 2.5 V and exceeds the voltage level of the thresholdVIH_DLC2, and therefore, the camera controller 101 determines that theDLC2 terminal outputs the High-level voltage. Therefore, the High-levelvoltage is input to the DLC2 input terminal (DLC2_IN) instead of theLow-level voltage, which is anticipated to be input. Accordingly, theabnormal state of the terminal can be detected in this case (errordetection). Then, the LCLK terminal 1008 keeps the output state of theopen drain type, and a warning is displayed to encourage the user tocheck the state of the terminals provided in each mount (errorprocessing).

With this configuration, even in the case where a short circuit occursbetween the LCLK terminal and the DLC2 terminal due to terminal bending,the LCLK terminal 1008 of the camera body 100 does not switch to aCMOS-output-type terminal, and the second/third communication I/F unit102 b can be protected from overvoltage.

When such switching is performed in accordance with the mountedinterchangeable lens so as to make the communication voltage of thesecond and third communication units equal to a voltage of the firstcommunication unit, a failure in an electric circuit that may occur in acase of a short circuit between terminals can be prevented. However, toreduce power consumption relating to communication and to makecommunication faster, the communication voltage of the second and thirdcommunication units are set so as to be equal to the lowest voltageamong the communication voltages of the first communication unit.

An embodiment of the present invention has been described above;however, the present invention is not limited to this, and variousmodifications and changes can be made. For example, in theabove-described embodiment, the case has been described where a digitalcamera is employed as an example of the camera body 100, which is animage capturing apparatus; however, an image capturing apparatus, suchas a digital video camera or a security camera, other than a digitalcamera may be employed.

In the above-described embodiment, the case has been described where aninterchangeable lens, an adapter, and an intermediate accessory areemployed as examples of the camera accessories of the present invention;however, the camera accessories are not limited to these. As the cameraaccessories, any device other than those described above may be employedas long as the device can be directly or indirectly coupled to (mountedon) the camera mount A of the camera body 100.

In the above-described embodiment, as illustrated in FIGS. 4A and 4B,the direction in which the lens mount B is rotated relative to thecamera mount A clockwise when the camera body 100 is viewed from theside that faces an object in a case of image capturing is defined as themount direction; however, the mount direction is not limited to this.For example, the direction in which the lens mount B is rotated relativeto the camera mount A counterclockwise when the camera body 100 isviewed from the side that faces an object in a case of image capturingmay be defined as the mount direction. In this case, at least theterminals disposed on each mount described above need to be arranged inthe reverse order.

The terms “furthest” and “nearest” in the mount direction of the lensmount described above indicate the positions within a range in which,when a camera accessory is mounted on the camera body 100, the terminalscorresponding to both the camera mount and the lens mount are present.Therefore, in a case where, for example, a terminal that is not includedin the camera body 100 is present in a mount of a camera accessory thatcan be mounted on the camera body 100, the position at which theterminal is disposed is not limited. Also for an image capturingapparatus on which each camera accessory described in theabove-described embodiment can be mounted, in a case where a terminalnot included in the camera accessory is present, the position at whichthe terminal is disposed is not limited.

In the above-described embodiment, the case has been described where theterminals provided in the mount of the image capturing apparatus arecontact pins, and the terminals provided in a mount of the accessory arecontact faces; however, the terminals are not limited to these. Forexample, a configuration may be employed in which contact faces areprovided in the mount of the image capturing apparatus, contact pinscorresponding to the contact faces are provided in a mount of theaccessory, and each of the contact faces and a corresponding one of thecontact pins can be electrically connected to each other. In this case,the features of the camera mount and those of the accessory mountdescribed in the above-described embodiment can be realized in thecorresponding accessory mount and lens mount.

Regarding the image capturing apparatus and the accessories according tothe above-described embodiment, in a case where, for example, theterminals provided in the camera mount are assumed to be contact faces,the width of each contact face provided in the camera mount in thecircumferential direction may be adjusted as appropriate. In a casewhere the terminals provided in the accessory mount are assumed to becontact pins, the inter-pin pitch for each contact pin provided in theaccessory mount may be adjusted as appropriate.

In the above-described embodiment, the case has been described where thecomputer program that follows the flows illustrated in FIG. 12 and FIG.13 is stored in advance in a memory (not illustrated) and the cameracontroller 101 executes the program; however, the present invention isnot limited to this. For example, the program may be in any form, suchas an object code, a program executed by an interpreter, or script datasupplied to the operating system (OS), as long as the program has thefunctions thereof. A recording medium that corresponds to the memoryfrom which the program is supplied may be, for example, a magneticrecording medium, such as a hard disk or a magnetic tape, or anoptical/magneto-optical recording medium.

Although a configuration has been described in the above embodimentwhere a device having one of a camera mount and an accessory mount isactually rotated as to a device having the other mount, therebybayonet-coupling the devices to each other, this is not restrictive. Forexample, a configuration may be employed where a camera mount andaccessory mount are relatively rotated, and the camera mount andaccessory mount are bayonet-coupled. Specifics of this will be describedin detail below.

FIG. 20 is a disassembled perspective view of a mount mechanism 5000according to a modification of the present invention. FIGS. 21A through21C are diagrams for exemplarily describing a non-coupled state of themount mechanism 5000 according to the modification of the presentinvention. FIGS. 22A through 22C are diagrams for exemplarily describinga coupled state of the mount mechanism 5000 according to themodification of the present invention. In FIGS. 20 through 22C, the lensmount that is capable of bayonet-coupling to a movable mount portion5010 of the mount mechanism 5000 is also illustrated, for the same ofdescription.

As illustrated in FIG. 20, the mount mechanism 5000 according to thepresent embodiment has, in order from the side to which the lens mountis attached, an operation portion 5030, a fixed mount portion 5020, themovable mount portion 5010, and the contact holding member 105, centeredon the optical axis 3000. The operation portion 5030 is ring-shapedoperating means capable of rotating on a center axis, and is fixed tothe movable mount portion 5010 by screws, by arm portions 5040. Notethat in the present modification, the operation portion 5030 and movablemount portion 5010 are fixed at two positions, using two arm portions5040 disposed in an orthogonal direction as to the center axis.According to this configuration, by the operation portion 5030 beingrotationally operated, the movable mount portion 5010 also rotatesintegrally with the center axis as the center.

Provided on the movable mount portion 5010 are movable mount claws 5011a, 5011 b, and 5011 c, that are each capable of bayonet-coupling withbayonet claws 301 a through 301 c provided to the lens mount. Alsoprovided to the movable mount portion 5010 is a screw portion 5012 thathas been threaded around the center axis, and the screwed state as to alater-described screw portion 5022 of the fixed mount portion 5020changes in accordance with the rotation of the movable mount portion5010 around the center axis.

The fixed mount portion 5020 has a camera mount face 5021 that comesinto contact with the mount face of the lens mount, and the screwportion 5022 with which the screw portion 5012 of the above-describedmovable mount portion 5010 is screwed. Unlike the above-describedmovable mount portion 5010, the fixed mount portion 5020 does not rotateon the center axis in accordance with rotation operations of theoperation portion 5030.

Next, the bayonet coupling method of the mount mechanism 5000 accordingto the present modification will be described with reference to FIGS.21A through 22C. Note that the bayonet claws provided to the lens mountare in a state of being capable to engage the movable mount claws 5011 athrough 5011 c of the movable mount portion 5010, in a state of beingpassed through an opening portion of the operation portion 5030 and anopening portion of the fixed mount portion 5020. The state illustratedin FIGS. 21A through 21C is a state where the operation portion 5030 issituated at an unlocked position. In this state, the lens mount face ofthe lens mount and the camera mount face 5021 of the fixed mount portion5020 are in contact, but the claws of each of the lens mount and movablemount portion 5010 do not engage each other, and do not overlap, asviewed from the center axis direction. FIG. 21C is a cross-sectionaldiagram taken along cross-section XXIC-XXIC in FIG. 21B. FIGS. 22Athrough 22C exemplify the mount mechanism 5000 in a state where theoperation portion 5030 has been rotationally operated from this state.

The state illustrated in FIGS. 22A through 22C is a state where theoperation portion 5030 is situated in a locked position. In this state,the claws of each of the lens mount and movable mount portion 5010overlap each other, and thereby are engaged in the center axisdirection. In this state, the screwing state of the screw portion 5022of the fixed mount portion 5020 and the screw portion 5012 of themovable mount portion 5010 changes in accordance with rotationaloperation of the operation portion 5030, and the movable mount portion5010 moves toward the imaging device side in the center axis direction.FIG. 22C is a cross-sectional diagram taken along cross-sectionXXIIC-XXIIC in FIG. 22B. As illustrated in FIGS. 21C and 22C, themovable mount portion 5010 moves away from the fixed mount portion 5020in a center axis direction of the mount depend on a non-locking state ofthe mount mechanism 5000 changing in a lock state of the mount mechanism5000. According to this configuration, each of the movable mount claws5011 a through 5011 c in a state of being engaged with the bayonet clawsat the lens mount side moves toward the imaging apparatus side.

As described above, the mount mechanism 5000 can move the movable mountportion in the center axis direction as to the fixed mount portion, byrotating the movable mount portion that has claws capable of engaginglens-mount-side claws on the center axis. According to thisconfiguration, the mount mechanism 5000 according to the presentembodiment can reduce occurrence of gaps (looseness) that occurs betweenthe lens mount and camera-side mount in a coupled state.

Although a configuration has been described in the above modificationwhere the mount mechanism 5000 is provided to the imaging apparatusside, this can be applied to a configuration where the mount mechanism5000 is provided to a camera accessory side, such as an interchangeablelens or the like.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2017-108273 filed May 31, 2017, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A mount apparatus comprising a second mountconfigured to allow coupling to a first mount included in an accessory,the accessory being mountable on and dismountable from the mountapparatus by rotating a plurality of claw portions of the first mountrelative to a plurality of claw portions of the second mount in a mountdirection substantially orthogonal to a center-axis direction of thesecond mount, wherein the mount apparatus includes a plurality ofterminals disposed in a circumferential direction of the second mountand configured to be used in electrical connection, and a terminalholder configured to hold the plurality of terminals, the terminalholder has a height level difference for holding the plurality ofterminals at different positions in the center-axis direction of thesecond mount, the plurality of terminals include a first terminalconfigured to be used to supply power for driving an internal componentof the accessory, a second terminal configured to indicate a groundlevel corresponding to the first terminal, and a third terminalconfigured to detect a type of the accessory mounted on the mountapparatus, the terminal holder has a first stage and a second stage atdifferent positions in the center-axis direction of the second mount, ina state where the accessory is mounted on the mount apparatus, thesecond stage projects toward the accessory in the center-axis directionfurther than the first stage, the first stage is located nearer than thesecond stage in a mount direction of the accessory, wherein, among theplurality of terminals, the first terminal and the third terminal aredisposed adjacent to each other and the second terminal and the thirdterminal are disposed adjacent to each other on the second stage of theterminal holder, and the second terminal is disposed nearer in the mountdirection of the accessory than the first terminal and the thirdterminal of the plurality of terminals on the second stage of theterminal holder.
 2. The mount apparatus according to claim 1, whereinthe second terminal is connected to a corresponding one of a pluralityof terminals of the accessory first among the plurality of terminalswhen the accessory is mounted on the mount apparatus, and wherein thesecond terminal is disconnected from the corresponding one of theterminals of the accessory last among the plurality of terminals whenthe accessory mounted on the mount apparatus is dismounted.
 3. The mountapparatus according to claim 1, wherein among the plurality ofterminals, the number of terminals disposed on the first stage isdifferent from the number of terminals disposed on the second stage. 4.The mount apparatus according to claim 1, wherein among the plurality ofterminals, the number of terminals disposed on the second stage issmaller than the number of terminals disposed on the first stage.
 5. Themount apparatus according to claim 4, wherein the plurality of terminalsare contact pins electrically connectable to the plurality of terminalsof the accessory, a second pitch between the second terminal and anotherterminal adjacent to the second terminal on the second stage of theterminal holder is wider than a first pitch between the terminalsdisposed on the first stage of the terminal holder, and when theaccessory is mounted on the mount apparatus, at least each of theplurality of terminals for which the first pitch is set do notsimultaneously come into contact with two or more terminals among theplurality of terminals of the accessory.
 6. The mount apparatusaccording to claim 5, wherein a pitch between the second terminal andthe third terminal is the second pitch, and a pitch between the firstterminal and the third terminal is the first pitch.
 7. The mountapparatus according to claim 5, wherein the plurality of terminalsinclude a fourth terminal disposed on the second stage of the terminalholder further in the mount direction of the accessory than the otherterminals, the fourth terminal is adjacent to the first terminal, and apitch between the first terminal and the fourth terminal is equal to thesecond pitch.
 8. The mount apparatus according to claim 7, wherein thefourth terminal is a terminal configured to supply communication powerto the accessory from the mount apparatus in a case where the accessoryis mounted on the mount apparatus.
 9. The mount apparatus according toclaim 8, wherein the plurality of terminals include a fifth terminallocated further than the other terminals in the mount direction of theaccessory on the first stage, and the fifth terminal is configured to beused to detect mounting of the accessory on the mount apparatus.
 10. Themount apparatus according to claim 9, wherein the plurality of terminalsinclude a sixth terminal located nearer than the other terminals in themount direction of the accessory on the first stage, and the sixthterminal is configured to indicate a ground level corresponding to thefourth terminal.
 11. The mount apparatus according to claim 1, whereinthe plurality of terminals include a seventh terminal through a twelfthterminal on the first stage, and the seventh terminal through thetwelfth terminal are configured to be used to communicate to theaccessory and to be disposed between the fifth terminal and the sixthterminal.
 12. The mount apparatus according to claim 4, wherein theplurality of terminals are contact faces electrically connectable to theplurality of terminals of the accessory, and the second terminal has alargest width among the plurality of terminals in the circumferentialdirection of the second mount.
 13. The mount apparatus according toclaim 1, wherein the second terminal is disposed nearer to the firststage than the other terminals in the mount direction of the accessoryon the second stage.
 14. The mount apparatus according to claim 1,wherein the mount apparatus is provided on an imaging apparatus or anadapter device being mountable on and dismountable from an imagingapparatus.
 15. An accessory comprising a first mount configured to allowcoupling to a second mount included in a mount apparatus, the accessorybeing mountable on and dismountable from the mount apparatus by rotatinga plurality of claw portions of the first mount relative to a pluralityof claw portions of the second mount in a mount direction substantiallyorthogonal to a center-axis direction, wherein the accessory includes aplurality of terminals disposed in a circumferential direction of thesecond mount and configured to be used in electrical connection, and aterminal holder configured to hold the plurality of terminals, theterminal holder has a height level difference for holding the pluralityof terminals at different positions in the center-axis direction of thesecond mount, the plurality of terminals include a first terminalconfigured to receive power for driving an internal component of theaccessory from the mount apparatus, a second terminal configured toindicate a ground level corresponding to the first terminal, and a thirdterminal configured to be used for indicating a type of the accessory,the terminal holder has a first stage and a second stage at differentpositions in the center-axis direction of the first mount, in a statewhere the accessory is mounted on the mount apparatus, the first stageprojects towards the mount apparatus in the center-axis directionfurther than the second stage, the first stage is located nearer thanthe second stage in a mount direction of the accessory, wherein, amongthe plurality of terminals, the first terminal and the third terminalare disposed adjacent to each other and the second terminal and thethird terminal are disposed adjacent to each other on the second stageof the terminal holder, and the second terminal is disposed nearer inthe mount direction of the accessory than the first terminal and thethird terminal of the plurality of terminals on the second stage of theterminal holder.
 16. The accessory according to claim 15, wherein thesecond terminal is connected to a corresponding one of a plurality ofterminals of the mount apparatus first among the plurality of terminalswhen the accessory is mounted on the mount apparatus, and the secondterminal is disconnected from the corresponding one of the terminals ofthe mount apparatus last among the plurality of terminals when theaccessory mounted on the mount apparatus is dismounted.
 17. Theaccessory according to claim 16, wherein the plurality of terminals arecontact faces electrically connectable to the plurality of terminals ofthe mount apparatus, and the second terminal has a largest width amongthe plurality of terminals in the circumferential direction of thesecond mount.
 18. The accessory according to claim 17, wherein the thirdterminal has a width narrower than a width of the second terminal in thecircumferential direction of the second mount.
 19. The accessoryaccording to claim 17, wherein the plurality of terminals include afourth terminal disposed on the second stage of the terminal holderfurther in the mount direction of the accessory than the otherterminals, the fourth terminal is adjacent to the first terminal, andthe fourth terminal has a width narrower than the width of the secondterminal in the circumferential direction of the second mount.
 20. Theaccessory according to claim 19, wherein the fourth terminal is aterminal configured to receive communication power from the mountapparatus in a case where the accessory is mounted on the mountapparatus.
 21. The accessory according to claim 20, wherein theplurality of terminals include a fifth terminal located further than theother terminals in the mount direction of the accessory on the firststage, and the fifth terminal is configured to be used to detectmounting of the accessory on the mount apparatus.
 22. The accessoryaccording to claim 21, wherein the plurality of terminals include asixth terminal located nearer than the other terminals in the mountdirection of the accessory on the first stage, and the sixth terminal isconfigured to indicate a ground level corresponding to the fourthterminal.
 23. The accessory according to claim 22, wherein the pluralityof terminals include a seventh terminal through a twelfth terminal onthe first stage, and the seventh terminal through the twelfth terminalare configured to be used to communicate to the mount apparatus and tobe disposed between the fifth terminal and the sixth terminal.
 24. Theaccessory according to claim 15, wherein among the plurality ofterminals, the number of terminals disposed on the first stage isdifferent from the number of terminals disposed on the second stage. 25.The accessory according to claim 15, wherein among the plurality ofterminals, the number of terminals disposed on the second stage issmaller than the number of terminals disposed on the first stage. 26.The accessory according to claim 15, wherein the second terminal isdisposed nearer to the first stage than the other terminal in the mountdirection of the accessory on the second stage.
 27. The accessoryaccording to claim 15, wherein the accessory is an interchangeable lensor a first adapter device being mountable on and dismountable from themount apparatus, and wherein the mount apparatus is provided on animaging apparatus or a second adapter device being mountable on anddismountable from an imaging apparatus.